ash_authentication

Summary

Insertion of Sensitive Information into Log File vulnerability in team-alembic AshAuthentication allows disclosure of user password digests to readers of the audit store.

The audit_log add-on builds each entry's extra_data in AshAuthentication.AddOn.AuditLog.Auditor.build_extra_data/4, which takes :actor from the action callback context verbatim. Any audited action invoked with actor: set to a user record therefore deposits that record, including its hashed_password attribute, into the audit entry. The same module already collapses the audited identity to an opaque string via AshAuthentication.user_to_subject/1 and filters params against the strategy's configured allow-list, so the actor is the only stored value that reaches the audit store unfiltered. Marking the attribute sensitive?: true does not help, because that redacts inspect/1 output rather than JSON encoding or raw-term storage.

There is no attacker-controlled trigger and no network disclosure path: entries accumulate from ordinary authenticated activity, and an attacker's own requests deposit only their own digest. Exploitation requires independent read access to the audit store, such as database credentials, an audit role, a backup, or a log shipper, at which point the digests support offline password attack against every active account. Whether the material persists depends on the data layer, since raw-term stores keep it verbatim while a SQL store raises Protocol.UndefinedError and drops the entry unless the user resource derives Jason.Encoder.

This issue affects ash_authentication: from 4.12.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.2.

Summary

Insertion of Sensitive Information into Log File vulnerability in team-alembic AshAuthentication allows disclosure of user password digests to readers of the audit store.

The audit_log add-on builds each entry's extra_data in AshAuthentication.AddOn.AuditLog.Auditor.build_extra_data/4, which takes :actor from the action callback context verbatim. Any audited action invoked with actor: set to a user record therefore deposits that record, including its hashed_password attribute, into the audit entry. The same module already collapses the audited identity to an opaque string via AshAuthentication.user_to_subject/1 and filters params against the strategy's configured allow-list, so the actor is the only stored value that reaches the audit store unfiltered. Marking the attribute sensitive?: true does not help, because that redacts inspect/1 output rather than JSON encoding or raw-term storage.

There is no attacker-controlled trigger and no network disclosure path: entries accumulate from ordinary authenticated activity, and an attacker's own requests deposit only their own digest. Exploitation requires independent read access to the audit store, such as database credentials, an audit role, a backup, or a log shipper, at which point the digests support offline password attack against every active account. Whether the material persists depends on the data layer, since raw-term stores keep it verbatim while a SQL store raises Protocol.UndefinedError and drops the entry unless the user resource derives Jason.Encoder.

This issue affects ash_authentication: from 4.12.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.2.

Summary

Session Fixation vulnerability in team-alembic ash_authentication allows an attacker who can plant a session identifier in a victim's browser to hold an authenticated session once that victim signs in.

AshAuthentication.Plug.Helpers.store_in_session/2 writes the authenticated subject into the existing session with Plug.Conn.put_session/3 and never calls Plug.Conn.configure_session(renew: true), so the identifier the visitor arrived with carries into their authenticated session. Every authentication event reaches this one function: the default success/4 injected by AshAuthentication.Phoenix.Controller.__using__/1, the AuthController emitted by mix ash_authentication_phoenix.install, and remember-me auto-login. AshAuthentication.Phoenix.Plug.store_in_session/2 is a defdelegate to it. Logout does not close the window either, because clear_session/2 ends with Plug.Conn.clear_session/1, which clears session contents but leaves the identifier intact, so a planted identifier survives a logout-then-login cycle.

This issue affects ash_authentication: from 0.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Impact

An attacker holding a session identifier they planted before the victim signed in gains that victim's authenticated session, and with it full account takeover, in deployments using a server-side session store.

Workarounds

Call Plug.Conn.configure_session(conn, renew: true) in your own success/4 before store_in_session/2. This is a one-line change in application code and closes the controller sign-in path, though not remember-me auto-login, which does not pass through application code.

Add Plug.Conn.configure_session(conn, drop: true) at sign-out so a planted identifier does not survive a logout-then-login cycle.

Configurations

Exploitation for account takeover requires a server-side session store (ETS, Mnesia, Redis or a database), where the cookie carries a stable session identifier, and a position from which the attacker can plant that cookie in the victim's browser: cookie tossing from a sibling subdomain, an HTTP host without HSTS, or a shared or kiosk browser.

Phoenix defaults to the signed cookie store, and neither package's installer changes it. Under that store the authenticated session lives in the re-signed cookie delivered only to the victim, so a planted pre-authentication copy does not become an authenticated session. Attacker-planted session contents, such as a return_to value, still survive into the authenticated session there.

Summary

Authentication Bypass by Spoofing vulnerability in team-alembic ash_authentication allows an attacker who can plant a remember-me cookie in a victim's browser to replace that victim's authenticated session with one for the attacker's own account.

AshAuthentication.Plug.Helpers.sign_in_using_remember_me/3 skips re-authenticating an already-signed-in visitor by checking the session for "<subject_name>_token", but store_in_session/2 writes that key only when require_token_presence_for_authentication? is enabled and otherwise writes the bare subject name. At the default setting the guard therefore reads a key that is never written, its already-signed-in branch is unreachable, and the remember-me sign-in runs on every request through the per-request browser pipeline plug. A planted remember-me cookie is consequently honoured even for a visitor holding a live authenticated session, so whatever the victim enters afterwards lands in data the attacker controls. The read path in authenticate_resource_from_session/4 selects the key correctly, so the guard and the reader disagree about which key holds the session.

This issue affects ash_authentication: from 4.10.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Impact

An attacker who can set a remember-me cookie in a victim's browser silently replaces the victim's authenticated session with one for the attacker's own account, so data the victim subsequently enters is written to records the attacker controls. The victim is given no indication their identity changed.

Workarounds

Set require_token_presence_for_authentication? true on the authenticated resource's token configuration. store_in_session/2 then writes the key the guard reads, so the already-signed-in branch fires and the remember-me sign-in no longer runs against a live session. Note this changes session storage semantics for the whole application and requires a token resource.

Otherwise remove the remember-me plug from the browser pipeline, which disables remember-me auto-login entirely.

Configurations

The application must enable the remember_me strategy and run its per-request plug in the browser pipeline, with require_token_presence_for_authentication? at its default of false. Enabling that setting makes the guard read the key the session actually holds, which closes the issue.

The attacker also needs a position from which to set a cookie in the victim's browser, such as cookie tossing from a sibling subdomain, an HTTP host without HSTS, or a shared or kiosk browser.

Summary

Improper Authentication vulnerability in team-alembic AshAuthentication allows an attacker to be signed in as another user by linking an OAuth2 identity to an account that is not theirs.

AshAuthentication.Strategy.OAuth2.UserResolver.resolve/3 matches an existing account using the register action's upsert_identity keys, then gates linking the incoming provider identity to it on email_trusted?/2, which reads only the provider's email_verified boolean and never compares the provider's email value with the matched account's email. That gate assumes the account was matched by its email field, so under any other upsert_identity it is vacuous and an attacker presenting their own verified email is attached to, and issued a session for, an account matched on some other attribute. The same unguarded gate applies in OAuth2.SignInPreparation on the registration_enabled? false path, where the account is matched by the sign-in action's read filter instead. The upsert also rewrites the matched account's email to the attacker's address, so later account recovery reaches the attacker rather than the owner.

This issue affects ash_authentication: from 4.14.0 before 4.15.0 and from 5.0.0-rc.10 before 5.0.0-rc.14.

Impact

An attacker who controls a provider account with a verified email of their own is signed in as a different local user, holding a session bearing that user's subject, with no interaction from the victim and no need to pre-register. Because the link also rewrites the matched account's email to the attacker's address, account recovery for the victim is redirected to the attacker and the compromise survives the provider identity being unlinked.

Workarounds

Set trust_email_verified? false on the affected strategy, which refuses the sign-in rather than linking it and closes both the register and the sign-in path.

Alternatively, key the register action's upsert_identity, or the sign-in action's read filter, on the email attribute, which restores the premise the gate assumes.

Configurations

The strategy must have trust_email_verified? enabled, and the account must be matched on something other than the email: a register action whose upsert_identity keys are not the email attribute, or, with registration_enabled? false, a sign-in action whose read filter is not the email.

trust_email_verified? defaults to false on the base oauth2 strategy, but the apple, auth0, github, google and slack strategies each set it to true in their own DSL.

Solutions

Upgrading prevents new links but does not unpick existing ones. An account already linked through this path stays linked, and a victim's email may already have been rewritten to the attacker's address.

Operators whose register action or sign-in action matched on anything other than the email should review their UserIdentity rows for links whose provider email does not match the linked account's email, and check affected accounts for a rewritten email address.

Summary

Authentication Bypass by Primary Weakness vulnerability in team-alembic AshAuthentication allows an unconfirmed user to obtain a session, defeating a mandatory email confirmation requirement.

AshAuthentication.Strategy.Password.Actions.check_user/2 decides whether the attribute named by require_confirmed_with is set using a bare is_nil(Map.get(user, value)). When that attribute is not selected on the loaded record Map.get/2 returns %Ash.NotLoaded{}, and when a field policy denies it for the current actor it returns %Ash.ForbiddenField{}. Neither is nil, so the rejection branch is skipped and sign-i

require_confirmed_with is enforced in two places, and neither holds in every configuration. sign_in_with_token and register are checked only inside AshAuthentication.Strategy.Password.Actions, not on the action itself, so any caller that invokes the action directly skips the check. An API layer such as AshGraphql or AshJsonApi invokes the action directly, so this applies to the default configuration. Where a check does run it compares the confirmation attribute against nil. That attribute holds %Ash.NotLoaded{} or %Ash.ForbiddenField{} when it sets select_by_default?: false, when an API layer narrows the read's select, or when a field policy hides it from the sign-in actor. Neither struct is nil, so those configurations read every user as confirmed.

This issue affects ash_authentication: from 4.3.8 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Insufficient Session Expiration vulnerability in team-alembic AshAuthentication and AshAuthentication Phoenix allows a revoked session to remain fully authenticated.

A resource configured with session_identifier :jti and require_token_presence_for_authentication? disabled stores its session value as <jti>:<subject>. The jti is there so that signing out can revoke that one session. Neither reader consults it: AshAuthentication.Plug.Helpers.authenticate_resource_from_session/4 and AshAuthentication.Phoenix.LiveSession.on_mount/4 both split the value with split_identifier/2, discard the jti and pass the bare subject to AshAuthentication.subject_to_user/3, which reloads the record. The token-presence branch of each function does check its token, calling AshAuthentication.TokenResource.Actions.get_token/3 with the jti and the purpose user. Because the revocation record is never read, neither its revoked state nor its expiry constrains the session, so a session captured before sign-out keeps working.

This issue affects ash_authentication: from 4.9.1 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14; ash_authentication_phoenix: from 2.10.0 before 2.17.4 and from 3.0.0-rc.0 before 3.0.0-rc.11.

Summary

Use of HTTP Request With Sensitive Query String vulnerability in team-alembic AshAuthenticationPhoenix allows someone able to read access logs, proxy logs or browser history to recover a single-use sign-in token and authenticate as its owner.

After a successful password sign-in, AshAuthentication.Phoenix.Components.Password.SignInForm builds the sign_in_with_token path with the freshly issued user.__metadata__.token as a query parameter and redirects the browser to it with a GET. The token therefore travels in the request line, where web servers, reverse proxies, request telemetry and the browser's own history record it, all of which outlive the request and are ordinarily less protected than session storage. The redirect destination is restricted to a local path, so this is not an open redirect; the exposure is the retention of a live credential.

This issue affects ash_authentication_phoenix: from 1.7.0 before 2.17.4 and from 3.0.0-rc.0 before 3.0.0-rc.11; ash_authentication: from 3.10.5 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Improper Authentication vulnerability in team-alembic AshAuthentication allows an attacker holding a sign-in token for one authenticated resource to be signed in as a user of a different resource.

AshAuthentication.Strategy.Password.SignInWithTokenPreparation.extract_primary_keys_from_subject/2 parses the JWT sub claim (for example user?id=1) with URI.parse/1 and keeps only its query string, discarding the path segment that names the subject the token was issued for. Nothing else restores that binding: AshAuthentication.Jwt.verify/3 checks the signature, exp, nbf, jti and the library-version claims, the purpose check only requires sign_in, and the remaining comparison is over primary-key field names, which are identical across resources. The WebAuthn sign-in and remember-me preparations carry copies of the same helper and drop the path in the same way. The magic link sign-in path pins the subject name against the resource and is not affected.

This issue affects ash_authentication: from 3.10.5 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Improper Verification of Cryptographic Signature vulnerability in team-alembic AshAuthentication allows a caller of the token revocation action to neutralise a revocation or write arbitrary rows into the token resource.

AshAuthentication.TokenResource.RevokeTokenChange.change/3 reads the :token argument and decodes it with AshAuthentication.Jwt.peek/1, which delegates to Joken.peek_claims/1 and performs no signature check, unlike Jwt.verify/4. The jti, exp and sub claims it returns are written straight onto the revocation record, guarded only by byte_size(token) > 0. Because expires_at derives from the attacker-chosen exp, a forged copy of a genuine token that keeps the real jti but backdates exp yields a revocation row that is already expired: expunge_expired removes it and the genuine token passes revoked? again. Arbitrary jti and sub values can be inserted the same way.

This issue affects ash_authentication: from 0.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Improper Output Neutralization for Logs vulnerability in team-alembic AshAuthentication allows an unauthenticated attacker to forge application log entries by submitting a password reset identity containing newlines or control characters.

AshAuthentication.Strategy.Password.RequestPasswordReset.run/3 interpolates the identity argument, the email or username taken straight from the reset request, into its Logger.warning/1 heredocs without escaping, truncating or type-restricting it. The resource logged beside it is passed through inspect/1, which would have neutralized the value. A newline in the identity therefore ends the log record, and everything after it is written as a line of its own, so an attacker chooses the severity tag and the content of entries that appear to have come from the application.

This issue affects ash_authentication: from 4.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Insufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 state value to replay the callback and sign that victim into an attacker-controlled account.

AshAuthentication.Strategy.OAuth2.Plug.callback/2 clears the stored session_params through a rebinding step inside its with chain, conn <- delete_session(conn, session_key). Elixir evaluates the else block in the scope enclosing the with, so every failure path (the provider returning ?error=access_denied, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches store_authentication_result/2 holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry.

This issue affects ash_authentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in team-alembic AshAuthentication allows an attacker holding a leaked magic link to replay its single-use token and authenticate as the target subject. A magic link configured with single_use_token?, which is the default, is meant to be redeemable exactly once, but nothing serialises the token's validity check against its consumption, so concurrent redemptions of one token all succeed and each yields a full user token.

Sign-in verifies the JWT with Jwt.verify/4 and revokes it only afterwards: AshAuthentication.Strategy.MagicLink.SignInPreparation revokes in a Query.after_action callback, and AshAuthentication.Strategy.MagicLink.SignInChange in an after_transaction hook that runs once the sign-in has already committed. AshAuthentication.TokenResource.Actions.revoke/3 writes the revocation as an upsert, so a concurrent duplicate revocation silently succeeds instead of conflicting and no request ever loses the race.

This issue affects ash_authentication: from 3.9.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Authorization Bypass Through User-Controlled Key vulnerability in team-alembic AshAuthentication allows an authenticated attacker to overwrite and confirm another user's email address, and so take over that account. A confirmation token issued to one user is accepted on any other user's record.

AshAuthentication.AddOn.Confirmation.ConfirmChange verifies the token's signature and its act claim, then applies the changes stored against that token to whichever record the changeset targets, never comparing the sub claim against changeset.data. An attacker who registers an account and changes their own email replays the resulting token against a victim's record id, writing in their own address with force_change_attributes/2 and stamping confirmed_at, after which an ordinary password reset yields the account. The library's own confirmation flow is unaffected, because AshAuthentication.AddOn.Confirmation.Actions.confirm/3 resolves sub to a user and targets that record.

This issue affects ash_authentication: from 0.5.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Inefficient Algorithmic Complexity vulnerability in team-alembic AshAuthentication allows an unauthenticated attacker to exhaust CPU and memory via an oversized base62 segment in a submitted API key.

AshAuthentication.Base.decode62/1 in lib/ash_authentication/base.ex splits its argument into one binary per character and folds it with charval62/2, which recomputes Integer.pow(62, index) at every position instead of accumulating by Horner's method, so cost grows roughly cubically in the input length. bindecode62/1 in the same module is quadratic through Integer.undigits/2 and Integer.digits/2. Neither function caps byte_size/1, and AshAuthentication.Strategy.ApiKey.SignInPreparation passes the underscore-separated segments of the submitted key straight into both, before any key lookup and without prior authentication. The surrounding rescue clauses catch exceptions, not CPU or memory exhaustion.

This issue affects ash_authentication: from 4.8.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Use of a One-Way Hash with a Predictable Salt vulnerability in team-alembic AshAuthentication allows readers of the audit store to recover the client IP addresses that the audit log add-on's :hash privacy mode is meant to pseudonymise.

AshAuthentication.AddOn.AuditLog.IpPrivacy.hash_ip/1 computes a single unkeyed :crypto.hash(:sha256, salt <> ip) and truncates the result to 16 hexadecimal characters. The salt is read from the :audit_log_ip_salt or :secret application config keys, and falls back to the constant "default-salt-change-in-production" published in the library source when neither is set, with nothing warning that the default is in use. The IPv4 space is only 2^32 values and SHA-256 is fast, so the whole hash table is precomputable and every stored value maps back to its source address. Truncating to 16 characters does not help, and even a configured salt leaves the hash cheap enough to enumerate once it leaks.

This issue affects ash_authentication: from 4.12.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Configurations

Only applications that enable the audit_log add-on and set its ip_privacy mode to :hash store the affected value. Other modes (:none, :truncate, :exclude) do not reach hash_ip/1.

The complete break additionally requires the default salt, that is neither :audit_log_ip_salt nor :secret configured under the :ash_authentication application. This is the out-of-the-box state: no warning or error is raised when the hardcoded salt is in use.

Summary

Insertion of Sensitive Information into Log File vulnerability in team-alembic AshAuthentication allows disclosure of user password digests to readers of the audit store.

The audit_log add-on builds each entry's extra_data in AshAuthentication.AddOn.AuditLog.Auditor.build_extra_data/4, which takes :actor from the action callback context verbatim. Any audited action invoked with actor: set to a user record therefore deposits that record, including its hashed_password attribute, into the audit entry. The same module already collapses the audited identity to an opaque string via AshAuthentication.user_to_subject/1 and filters params against the strategy's configured allow-list, so the actor is the only stored value that reaches the audit store unfiltered. Marking the attribute sensitive?: true does not help, because that redacts inspect/1 output rather than JSON encoding or raw-term storage.

There is no attacker-controlled trigger and no network disclosure path: entries accumulate from ordinary authenticated activity, and an attacker's own requests deposit only their own digest. Exploitation requires independent read access to the audit store, such as database credentials, an audit role, a backup, or a log shipper, at which point the digests support offline password attack against every active account. Whether the material persists depends on the data layer, since raw-term stores keep it verbatim while a SQL store raises Protocol.UndefinedError and drops the entry unless the user resource derives Jason.Encoder.

This issue affects ash_authentication: from 4.12.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.2.

Summary

Session Fixation vulnerability in team-alembic ash_authentication allows an attacker who can plant a session identifier in a victim's browser to hold an authenticated session once that victim signs in.

AshAuthentication.Plug.Helpers.store_in_session/2 writes the authenticated subject into the existing session with Plug.Conn.put_session/3 and never calls Plug.Conn.configure_session(renew: true), so the identifier the visitor arrived with carries into their authenticated session. Every authentication event reaches this one function: the default success/4 injected by AshAuthentication.Phoenix.Controller.__using__/1, the AuthController emitted by mix ash_authentication_phoenix.install, and remember-me auto-login. AshAuthentication.Phoenix.Plug.store_in_session/2 is a defdelegate to it. Logout does not close the window either, because clear_session/2 ends with Plug.Conn.clear_session/1, which clears session contents but leaves the identifier intact, so a planted identifier survives a logout-then-login cycle.

This issue affects ash_authentication: from 0.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Impact

An attacker holding a session identifier they planted before the victim signed in gains that victim's authenticated session, and with it full account takeover, in deployments using a server-side session store.

Workarounds

Call Plug.Conn.configure_session(conn, renew: true) in your own success/4 before store_in_session/2. This is a one-line change in application code and closes the controller sign-in path, though not remember-me auto-login, which does not pass through application code.

Add Plug.Conn.configure_session(conn, drop: true) at sign-out so a planted identifier does not survive a logout-then-login cycle.

Configurations

Exploitation for account takeover requires a server-side session store (ETS, Mnesia, Redis or a database), where the cookie carries a stable session identifier, and a position from which the attacker can plant that cookie in the victim's browser: cookie tossing from a sibling subdomain, an HTTP host without HSTS, or a shared or kiosk browser.

Phoenix defaults to the signed cookie store, and neither package's installer changes it. Under that store the authenticated session lives in the re-signed cookie delivered only to the victim, so a planted pre-authentication copy does not become an authenticated session. Attacker-planted session contents, such as a return_to value, still survive into the authenticated session there.

Summary

Authentication Bypass by Spoofing vulnerability in team-alembic ash_authentication allows an attacker who can plant a remember-me cookie in a victim's browser to replace that victim's authenticated session with one for the attacker's own account.

AshAuthentication.Plug.Helpers.sign_in_using_remember_me/3 skips re-authenticating an already-signed-in visitor by checking the session for "<subject_name>_token", but store_in_session/2 writes that key only when require_token_presence_for_authentication? is enabled and otherwise writes the bare subject name. At the default setting the guard therefore reads a key that is never written, its already-signed-in branch is unreachable, and the remember-me sign-in runs on every request through the per-request browser pipeline plug. A planted remember-me cookie is consequently honoured even for a visitor holding a live authenticated session, so whatever the victim enters afterwards lands in data the attacker controls. The read path in authenticate_resource_from_session/4 selects the key correctly, so the guard and the reader disagree about which key holds the session.

This issue affects ash_authentication: from 4.10.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Impact

An attacker who can set a remember-me cookie in a victim's browser silently replaces the victim's authenticated session with one for the attacker's own account, so data the victim subsequently enters is written to records the attacker controls. The victim is given no indication their identity changed.

Workarounds

Set require_token_presence_for_authentication? true on the authenticated resource's token configuration. store_in_session/2 then writes the key the guard reads, so the already-signed-in branch fires and the remember-me sign-in no longer runs against a live session. Note this changes session storage semantics for the whole application and requires a token resource.

Otherwise remove the remember-me plug from the browser pipeline, which disables remember-me auto-login entirely.

Configurations

The application must enable the remember_me strategy and run its per-request plug in the browser pipeline, with require_token_presence_for_authentication? at its default of false. Enabling that setting makes the guard read the key the session actually holds, which closes the issue.

The attacker also needs a position from which to set a cookie in the victim's browser, such as cookie tossing from a sibling subdomain, an HTTP host without HSTS, or a shared or kiosk browser.

Summary

Authentication Bypass by Spoofing vulnerability in team-alembic ash_authentication allows an attacker who operates one identity-provider connection of a dynamic_oidc strategy to be signed in as a local user established through a different connection.

The strategy is meant to keep each connection in its own identity namespace by writing every UserIdentity row's strategy field as "<name>/<connection_id>", but that namespacing never takes effect. __connection_id__ is populated only on the ephemeral runtime struct built per request in dynamic_oidc/plug.ex, and DynamicOidc.IdentityChange.change/3 re-fetches the strategy from the compile-time DSL through Info.strategy_for_action, yielding the persisted struct whose __connection_id__ is its defstruct default of nil. OAuth2.identity_strategy_name/1 therefore falls back to the bare strategy name for both the identity write and the reads in oauth2/user_resolver.ex and oauth2/sign_in_preparation.ex. Since the identity resource's unique key is (uid, strategy), one row exists per sub across every connection, and the identity-match branch runs before any email check. Neither strategy handles iss, so nothing else distinguishes the issuers: OpenID Connect Core section 5.7 makes sub unique only within an issuer, so two connections numbering subjects independently share one subject space.

This issue affects ash_authentication: from 5.0.0-rc.10 before 5.0.0-rc.14.

Impact

An attacker who can obtain or choose their sub on any connection served by a dynamic_oidc strategy is authenticated as the local user established through a different connection, with no interaction from the victim and no pre-existing account on the application. Token, nonce and audience validation all pass legitimately, because they only prove the assertion came from the attacker's own identity provider.

The same collision also occurs with no attacker at all: two honest providers numbering subjects sequentially produce overlapping sub values and silently merge distinct users, so this may already have happened in affected deployments.

Configurations

Only deployments running a dynamic_oidc strategy with more than one identity-provider connection are exposed, since a single connection has no second namespace to collide with.

Two partial mitigations exist and neither is sufficient. A confirmation add-on incidentally blocks the takeover only while the victim is unconfirmed, leaving confirmed victims and confirmation-free applications exposed. Ash multitenancy isolates only a one-connection-per-tenant topology, so non-multitenant deployments and tenants holding several connections get no isolation; connection namespacing is orthogonal to tenancy.

Solutions

Upgrading is not sufficient on its own, for two reasons.

Namespacing changes the value the identity lookup keys on, so UserIdentity rows written before the fix, all holding the bare strategy name, no longer match. Each row's strategy must be relinked in place to "<name>/<connection_id>". Deleting the rows does not work: the block is the account match that follows, refused under the default on_untrusted_email_match :reject whether the row exists or not, and deleting also discards the stored refresh token. Where a deployment has one connection the mapping is unambiguous and the update is mechanical, but it must run in the same deployment as the upgrade and before users sign in, or a newly written namespaced row can collide with a surviving bare row on the (uid, strategy) index.

The fix also cannot separate accounts already merged, and the merge is not detectable from the database, because a collision never produced two rows to compare: the second user's identity was never created and the surviving row looks legitimate. Deployments running more than one connection must audit out of band, by exporting each connection's set of sub values from its identity provider and intersecting them. Any sub present in more than one set identifies an account that may have been merged.

Summary

Improper Authentication vulnerability in team-alembic AshAuthentication allows an attacker to be signed in as another user by linking an OAuth2 identity to an account that is not theirs.

AshAuthentication.Strategy.OAuth2.UserResolver.resolve/3 matches an existing account using the register action's upsert_identity keys, then gates linking the incoming provider identity to it on email_trusted?/2, which reads only the provider's email_verified boolean and never compares the provider's email value with the matched account's email. That gate assumes the account was matched by its email field, so under any other upsert_identity it is vacuous and an attacker presenting their own verified email is attached to, and issued a session for, an account matched on some other attribute. The same unguarded gate applies in OAuth2.SignInPreparation on the registration_enabled? false path, where the account is matched by the sign-in action's read filter instead. The upsert also rewrites the matched account's email to the attacker's address, so later account recovery reaches the attacker rather than the owner.

This issue affects ash_authentication: from 4.14.0 before 4.15.0 and from 5.0.0-rc.10 before 5.0.0-rc.14.

Impact

An attacker who controls a provider account with a verified email of their own is signed in as a different local user, holding a session bearing that user's subject, with no interaction from the victim and no need to pre-register. Because the link also rewrites the matched account's email to the attacker's address, account recovery for the victim is redirected to the attacker and the compromise survives the provider identity being unlinked.

Workarounds

Set trust_email_verified? false on the affected strategy, which refuses the sign-in rather than linking it and closes both the register and the sign-in path.

Alternatively, key the register action's upsert_identity, or the sign-in action's read filter, on the email attribute, which restores the premise the gate assumes.

Configurations

The strategy must have trust_email_verified? enabled, and the account must be matched on something other than the email: a register action whose upsert_identity keys are not the email attribute, or, with registration_enabled? false, a sign-in action whose read filter is not the email.

trust_email_verified? defaults to false on the base oauth2 strategy, but the apple, auth0, github, google and slack strategies each set it to true in their own DSL.

Solutions

Upgrading prevents new links but does not unpick existing ones. An account already linked through this path stays linked, and a victim's email may already have been rewritten to the attacker's address.

Operators whose register action or sign-in action matched on anything other than the email should review their UserIdentity rows for links whose provider email does not match the linked account's email, and check affected accounts for a rewritten email address.

Summary

Authentication Bypass by Primary Weakness vulnerability in team-alembic AshAuthentication allows an unconfirmed user to obtain a session, defeating a mandatory email confirmation requirement.

AshAuthentication.Strategy.Password.Actions.check_user/2 decides whether the attribute named by require_confirmed_with is set using a bare is_nil(Map.get(user, value)). When that attribute is not selected on the loaded record Map.get/2 returns %Ash.NotLoaded{}, and when a field policy denies it for the current actor it returns %Ash.ForbiddenField{}. Neither is nil, so the rejection branch is skipped and sign-i

require_confirmed_with is enforced in two places, and neither holds in every configuration. sign_in_with_token and register are checked only inside AshAuthentication.Strategy.Password.Actions, not on the action itself, so any caller that invokes the action directly skips the check. An API layer such as AshGraphql or AshJsonApi invokes the action directly, so this applies to the default configuration. Where a check does run it compares the confirmation attribute against nil. That attribute holds %Ash.NotLoaded{} or %Ash.ForbiddenField{} when it sets select_by_default?: false, when an API layer narrows the read's select, or when a field policy hides it from the sign-in actor. Neither struct is nil, so those configurations read every user as confirmed.

This issue affects ash_authentication: from 4.3.8 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Insufficient Session Expiration vulnerability in team-alembic AshAuthentication and AshAuthentication Phoenix allows a revoked session to remain fully authenticated.

A resource configured with session_identifier :jti and require_token_presence_for_authentication? disabled stores its session value as <jti>:<subject>. The jti is there so that signing out can revoke that one session. Neither reader consults it: AshAuthentication.Plug.Helpers.authenticate_resource_from_session/4 and AshAuthentication.Phoenix.LiveSession.on_mount/4 both split the value with split_identifier/2, discard the jti and pass the bare subject to AshAuthentication.subject_to_user/3, which reloads the record. The token-presence branch of each function does check its token, calling AshAuthentication.TokenResource.Actions.get_token/3 with the jti and the purpose user. Because the revocation record is never read, neither its revoked state nor its expiry constrains the session, so a session captured before sign-out keeps working.

This issue affects ash_authentication: from 4.9.1 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14; ash_authentication_phoenix: from 2.10.0 before 2.17.4 and from 3.0.0-rc.0 before 3.0.0-rc.11.

Summary

Use of HTTP Request With Sensitive Query String vulnerability in team-alembic AshAuthenticationPhoenix allows someone able to read access logs, proxy logs or browser history to recover a single-use sign-in token and authenticate as its owner.

After a successful password sign-in, AshAuthentication.Phoenix.Components.Password.SignInForm builds the sign_in_with_token path with the freshly issued user.__metadata__.token as a query parameter and redirects the browser to it with a GET. The token therefore travels in the request line, where web servers, reverse proxies, request telemetry and the browser's own history record it, all of which outlive the request and are ordinarily less protected than session storage. The redirect destination is restricted to a local path, so this is not an open redirect; the exposure is the retention of a live credential.

This issue affects ash_authentication_phoenix: from 1.7.0 before 2.17.4 and from 3.0.0-rc.0 before 3.0.0-rc.11; ash_authentication: from 3.10.5 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Improper Authentication vulnerability in team-alembic AshAuthentication allows an attacker holding a sign-in token for one authenticated resource to be signed in as a user of a different resource.

AshAuthentication.Strategy.Password.SignInWithTokenPreparation.extract_primary_keys_from_subject/2 parses the JWT sub claim (for example user?id=1) with URI.parse/1 and keeps only its query string, discarding the path segment that names the subject the token was issued for. Nothing else restores that binding: AshAuthentication.Jwt.verify/3 checks the signature, exp, nbf, jti and the library-version claims, the purpose check only requires sign_in, and the remaining comparison is over primary-key field names, which are identical across resources. The WebAuthn sign-in and remember-me preparations carry copies of the same helper and drop the path in the same way. The magic link sign-in path pins the subject name against the resource and is not affected.

This issue affects ash_authentication: from 3.10.5 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Improper Verification of Cryptographic Signature vulnerability in team-alembic AshAuthentication allows a caller of the token revocation action to neutralise a revocation or write arbitrary rows into the token resource.

AshAuthentication.TokenResource.RevokeTokenChange.change/3 reads the :token argument and decodes it with AshAuthentication.Jwt.peek/1, which delegates to Joken.peek_claims/1 and performs no signature check, unlike Jwt.verify/4. The jti, exp and sub claims it returns are written straight onto the revocation record, guarded only by byte_size(token) > 0. Because expires_at derives from the attacker-chosen exp, a forged copy of a genuine token that keeps the real jti but backdates exp yields a revocation row that is already expired: expunge_expired removes it and the genuine token passes revoked? again. Arbitrary jti and sub values can be inserted the same way.

This issue affects ash_authentication: from 0.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Improper Output Neutralization for Logs vulnerability in team-alembic AshAuthentication allows an unauthenticated attacker to forge application log entries by submitting a password reset identity containing newlines or control characters.

AshAuthentication.Strategy.Password.RequestPasswordReset.run/3 interpolates the identity argument, the email or username taken straight from the reset request, into its Logger.warning/1 heredocs without escaping, truncating or type-restricting it. The resource logged beside it is passed through inspect/1, which would have neutralized the value. A newline in the identity therefore ends the log record, and everything after it is written as a line of its own, so an attacker chooses the severity tag and the content of entries that appear to have come from the application.

This issue affects ash_authentication: from 4.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Insufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 state value to replay the callback and sign that victim into an attacker-controlled account.

AshAuthentication.Strategy.OAuth2.Plug.callback/2 clears the stored session_params through a rebinding step inside its with chain, conn <- delete_session(conn, session_key). Elixir evaluates the else block in the scope enclosing the with, so every failure path (the provider returning ?error=access_denied, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches store_authentication_result/2 holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry.

This issue affects ash_authentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in team-alembic AshAuthentication allows an attacker holding a leaked magic link to replay its single-use token and authenticate as the target subject. A magic link configured with single_use_token?, which is the default, is meant to be redeemable exactly once, but nothing serialises the token's validity check against its consumption, so concurrent redemptions of one token all succeed and each yields a full user token.

Sign-in verifies the JWT with Jwt.verify/4 and revokes it only afterwards: AshAuthentication.Strategy.MagicLink.SignInPreparation revokes in a Query.after_action callback, and AshAuthentication.Strategy.MagicLink.SignInChange in an after_transaction hook that runs once the sign-in has already committed. AshAuthentication.TokenResource.Actions.revoke/3 writes the revocation as an upsert, so a concurrent duplicate revocation silently succeeds instead of conflicting and no request ever loses the race.

This issue affects ash_authentication: from 3.9.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Authorization Bypass Through User-Controlled Key vulnerability in team-alembic AshAuthentication allows an authenticated attacker to overwrite and confirm another user's email address, and so take over that account. A confirmation token issued to one user is accepted on any other user's record.

AshAuthentication.AddOn.Confirmation.ConfirmChange verifies the token's signature and its act claim, then applies the changes stored against that token to whichever record the changeset targets, never comparing the sub claim against changeset.data. An attacker who registers an account and changes their own email replays the resulting token against a victim's record id, writing in their own address with force_change_attributes/2 and stamping confirmed_at, after which an ordinary password reset yields the account. The library's own confirmation flow is unaffected, because AshAuthentication.AddOn.Confirmation.Actions.confirm/3 resolves sub to a user and targets that record.

This issue affects ash_authentication: from 0.5.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Inefficient Algorithmic Complexity vulnerability in team-alembic AshAuthentication allows an unauthenticated attacker to exhaust CPU and memory via an oversized base62 segment in a submitted API key.

AshAuthentication.Base.decode62/1 in lib/ash_authentication/base.ex splits its argument into one binary per character and folds it with charval62/2, which recomputes Integer.pow(62, index) at every position instead of accumulating by Horner's method, so cost grows roughly cubically in the input length. bindecode62/1 in the same module is quadratic through Integer.undigits/2 and Integer.digits/2. Neither function caps byte_size/1, and AshAuthentication.Strategy.ApiKey.SignInPreparation passes the underscore-separated segments of the submitted key straight into both, before any key lookup and without prior authentication. The surrounding rescue clauses catch exceptions, not CPU or memory exhaustion.

This issue affects ash_authentication: from 4.8.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Use of a One-Way Hash with a Predictable Salt vulnerability in team-alembic AshAuthentication allows readers of the audit store to recover the client IP addresses that the audit log add-on's :hash privacy mode is meant to pseudonymise.

AshAuthentication.AddOn.AuditLog.IpPrivacy.hash_ip/1 computes a single unkeyed :crypto.hash(:sha256, salt <> ip) and truncates the result to 16 hexadecimal characters. The salt is read from the :audit_log_ip_salt or :secret application config keys, and falls back to the constant "default-salt-change-in-production" published in the library source when neither is set, with nothing warning that the default is in use. The IPv4 space is only 2^32 values and SHA-256 is fast, so the whole hash table is precomputable and every stored value maps back to its source address. Truncating to 16 characters does not help, and even a configured salt leaves the hash cheap enough to enumerate once it leaks.

This issue affects ash_authentication: from 4.12.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Configurations

Only applications that enable the audit_log add-on and set its ip_privacy mode to :hash store the affected value. Other modes (:none, :truncate, :exclude) do not reach hash_ip/1.

The complete break additionally requires the default salt, that is neither :audit_log_ip_salt nor :secret configured under the :ash_authentication application. This is the out-of-the-box state: no warning or error is raised when the hardcoded salt is in use.

Summary

Insertion of Sensitive Information into Log File vulnerability in team-alembic AshAuthentication allows disclosure of user password digests to readers of the audit store.

The audit_log add-on builds each entry's extra_data in AshAuthentication.AddOn.AuditLog.Auditor.build_extra_data/4, which takes :actor from the action callback context verbatim. Any audited action invoked with actor: set to a user record therefore deposits that record, including its hashed_password attribute, into the audit entry. The same module already collapses the audited identity to an opaque string via AshAuthentication.user_to_subject/1 and filters params against the strategy's configured allow-list, so the actor is the only stored value that reaches the audit store unfiltered. Marking the attribute sensitive?: true does not help, because that redacts inspect/1 output rather than JSON encoding or raw-term storage.

There is no attacker-controlled trigger and no network disclosure path: entries accumulate from ordinary authenticated activity, and an attacker's own requests deposit only their own digest. Exploitation requires independent read access to the audit store, such as database credentials, an audit role, a backup, or a log shipper, at which point the digests support offline password attack against every active account. Whether the material persists depends on the data layer, since raw-term stores keep it verbatim while a SQL store raises Protocol.UndefinedError and drops the entry unless the user resource derives Jason.Encoder.

This issue affects ash_authentication: from 4.12.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.2.

Summary

Session Fixation vulnerability in team-alembic ash_authentication allows an attacker who can plant a session identifier in a victim's browser to hold an authenticated session once that victim signs in.

AshAuthentication.Plug.Helpers.store_in_session/2 writes the authenticated subject into the existing session with Plug.Conn.put_session/3 and never calls Plug.Conn.configure_session(renew: true), so the identifier the visitor arrived with carries into their authenticated session. Every authentication event reaches this one function: the default success/4 injected by AshAuthentication.Phoenix.Controller.__using__/1, the AuthController emitted by mix ash_authentication_phoenix.install, and remember-me auto-login. AshAuthentication.Phoenix.Plug.store_in_session/2 is a defdelegate to it. Logout does not close the window either, because clear_session/2 ends with Plug.Conn.clear_session/1, which clears session contents but leaves the identifier intact, so a planted identifier survives a logout-then-login cycle.

This issue affects ash_authentication: from 0.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Impact

An attacker holding a session identifier they planted before the victim signed in gains that victim's authenticated session, and with it full account takeover, in deployments using a server-side session store.

Workarounds

Call Plug.Conn.configure_session(conn, renew: true) in your own success/4 before store_in_session/2. This is a one-line change in application code and closes the controller sign-in path, though not remember-me auto-login, which does not pass through application code.

Add Plug.Conn.configure_session(conn, drop: true) at sign-out so a planted identifier does not survive a logout-then-login cycle.

Configurations

Exploitation for account takeover requires a server-side session store (ETS, Mnesia, Redis or a database), where the cookie carries a stable session identifier, and a position from which the attacker can plant that cookie in the victim's browser: cookie tossing from a sibling subdomain, an HTTP host without HSTS, or a shared or kiosk browser.

Phoenix defaults to the signed cookie store, and neither package's installer changes it. Under that store the authenticated session lives in the re-signed cookie delivered only to the victim, so a planted pre-authentication copy does not become an authenticated session. Attacker-planted session contents, such as a return_to value, still survive into the authenticated session there.

Summary

Authentication Bypass by Spoofing vulnerability in team-alembic ash_authentication allows an attacker who can plant a remember-me cookie in a victim's browser to replace that victim's authenticated session with one for the attacker's own account.

AshAuthentication.Plug.Helpers.sign_in_using_remember_me/3 skips re-authenticating an already-signed-in visitor by checking the session for "<subject_name>_token", but store_in_session/2 writes that key only when require_token_presence_for_authentication? is enabled and otherwise writes the bare subject name. At the default setting the guard therefore reads a key that is never written, its already-signed-in branch is unreachable, and the remember-me sign-in runs on every request through the per-request browser pipeline plug. A planted remember-me cookie is consequently honoured even for a visitor holding a live authenticated session, so whatever the victim enters afterwards lands in data the attacker controls. The read path in authenticate_resource_from_session/4 selects the key correctly, so the guard and the reader disagree about which key holds the session.

This issue affects ash_authentication: from 4.10.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Impact

An attacker who can set a remember-me cookie in a victim's browser silently replaces the victim's authenticated session with one for the attacker's own account, so data the victim subsequently enters is written to records the attacker controls. The victim is given no indication their identity changed.

Workarounds

Set require_token_presence_for_authentication? true on the authenticated resource's token configuration. store_in_session/2 then writes the key the guard reads, so the already-signed-in branch fires and the remember-me sign-in no longer runs against a live session. Note this changes session storage semantics for the whole application and requires a token resource.

Otherwise remove the remember-me plug from the browser pipeline, which disables remember-me auto-login entirely.

Configurations

The application must enable the remember_me strategy and run its per-request plug in the browser pipeline, with require_token_presence_for_authentication? at its default of false. Enabling that setting makes the guard read the key the session actually holds, which closes the issue.

The attacker also needs a position from which to set a cookie in the victim's browser, such as cookie tossing from a sibling subdomain, an HTTP host without HSTS, or a shared or kiosk browser.

Summary

Authentication Bypass by Spoofing vulnerability in team-alembic ash_authentication allows an attacker who operates one identity-provider connection of a dynamic_oidc strategy to be signed in as a local user established through a different connection.

The strategy is meant to keep each connection in its own identity namespace by writing every UserIdentity row's strategy field as "<name>/<connection_id>", but that namespacing never takes effect. __connection_id__ is populated only on the ephemeral runtime struct built per request in dynamic_oidc/plug.ex, and DynamicOidc.IdentityChange.change/3 re-fetches the strategy from the compile-time DSL through Info.strategy_for_action, yielding the persisted struct whose __connection_id__ is its defstruct default of nil. OAuth2.identity_strategy_name/1 therefore falls back to the bare strategy name for both the identity write and the reads in oauth2/user_resolver.ex and oauth2/sign_in_preparation.ex. Since the identity resource's unique key is (uid, strategy), one row exists per sub across every connection, and the identity-match branch runs before any email check. Neither strategy handles iss, so nothing else distinguishes the issuers: OpenID Connect Core section 5.7 makes sub unique only within an issuer, so two connections numbering subjects independently share one subject space.

This issue affects ash_authentication: from 5.0.0-rc.10 before 5.0.0-rc.14.

Impact

An attacker who can obtain or choose their sub on any connection served by a dynamic_oidc strategy is authenticated as the local user established through a different connection, with no interaction from the victim and no pre-existing account on the application. Token, nonce and audience validation all pass legitimately, because they only prove the assertion came from the attacker's own identity provider.

The same collision also occurs with no attacker at all: two honest providers numbering subjects sequentially produce overlapping sub values and silently merge distinct users, so this may already have happened in affected deployments.

Configurations

Only deployments running a dynamic_oidc strategy with more than one identity-provider connection are exposed, since a single connection has no second namespace to collide with.

Two partial mitigations exist and neither is sufficient. A confirmation add-on incidentally blocks the takeover only while the victim is unconfirmed, leaving confirmed victims and confirmation-free applications exposed. Ash multitenancy isolates only a one-connection-per-tenant topology, so non-multitenant deployments and tenants holding several connections get no isolation; connection namespacing is orthogonal to tenancy.

Solutions

Upgrading is not sufficient on its own, for two reasons.

Namespacing changes the value the identity lookup keys on, so UserIdentity rows written before the fix, all holding the bare strategy name, no longer match. Each row's strategy must be relinked in place to "<name>/<connection_id>". Deleting the rows does not work: the block is the account match that follows, refused under the default on_untrusted_email_match :reject whether the row exists or not, and deleting also discards the stored refresh token. Where a deployment has one connection the mapping is unambiguous and the update is mechanical, but it must run in the same deployment as the upgrade and before users sign in, or a newly written namespaced row can collide with a surviving bare row on the (uid, strategy) index.

The fix also cannot separate accounts already merged, and the merge is not detectable from the database, because a collision never produced two rows to compare: the second user's identity was never created and the surviving row looks legitimate. Deployments running more than one connection must audit out of band, by exporting each connection's set of sub values from its identity provider and intersecting them. Any sub present in more than one set identifies an account that may have been merged.

Summary

Improper Authentication vulnerability in team-alembic AshAuthentication allows an attacker to be signed in as another user by linking an OAuth2 identity to an account that is not theirs.

AshAuthentication.Strategy.OAuth2.UserResolver.resolve/3 matches an existing account using the register action's upsert_identity keys, then gates linking the incoming provider identity to it on email_trusted?/2, which reads only the provider's email_verified boolean and never compares the provider's email value with the matched account's email. That gate assumes the account was matched by its email field, so under any other upsert_identity it is vacuous and an attacker presenting their own verified email is attached to, and issued a session for, an account matched on some other attribute. The same unguarded gate applies in OAuth2.SignInPreparation on the registration_enabled? false path, where the account is matched by the sign-in action's read filter instead. The upsert also rewrites the matched account's email to the attacker's address, so later account recovery reaches the attacker rather than the owner.

This issue affects ash_authentication: from 4.14.0 before 4.15.0 and from 5.0.0-rc.10 before 5.0.0-rc.14.

Impact

An attacker who controls a provider account with a verified email of their own is signed in as a different local user, holding a session bearing that user's subject, with no interaction from the victim and no need to pre-register. Because the link also rewrites the matched account's email to the attacker's address, account recovery for the victim is redirected to the attacker and the compromise survives the provider identity being unlinked.

Workarounds

Set trust_email_verified? false on the affected strategy, which refuses the sign-in rather than linking it and closes both the register and the sign-in path.

Alternatively, key the register action's upsert_identity, or the sign-in action's read filter, on the email attribute, which restores the premise the gate assumes.

Configurations

The strategy must have trust_email_verified? enabled, and the account must be matched on something other than the email: a register action whose upsert_identity keys are not the email attribute, or, with registration_enabled? false, a sign-in action whose read filter is not the email.

trust_email_verified? defaults to false on the base oauth2 strategy, but the apple, auth0, github, google and slack strategies each set it to true in their own DSL.

Solutions

Upgrading prevents new links but does not unpick existing ones. An account already linked through this path stays linked, and a victim's email may already have been rewritten to the attacker's address.

Operators whose register action or sign-in action matched on anything other than the email should review their UserIdentity rows for links whose provider email does not match the linked account's email, and check affected accounts for a rewritten email address.

Summary

Authentication Bypass by Primary Weakness vulnerability in team-alembic AshAuthentication allows an unconfirmed user to obtain a session, defeating a mandatory email confirmation requirement.

AshAuthentication.Strategy.Password.Actions.check_user/2 decides whether the attribute named by require_confirmed_with is set using a bare is_nil(Map.get(user, value)). When that attribute is not selected on the loaded record Map.get/2 returns %Ash.NotLoaded{}, and when a field policy denies it for the current actor it returns %Ash.ForbiddenField{}. Neither is nil, so the rejection branch is skipped and sign-i

require_confirmed_with is enforced in two places, and neither holds in every configuration. sign_in_with_token and register are checked only inside AshAuthentication.Strategy.Password.Actions, not on the action itself, so any caller that invokes the action directly skips the check. An API layer such as AshGraphql or AshJsonApi invokes the action directly, so this applies to the default configuration. Where a check does run it compares the confirmation attribute against nil. That attribute holds %Ash.NotLoaded{} or %Ash.ForbiddenField{} when it sets select_by_default?: false, when an API layer narrows the read's select, or when a field policy hides it from the sign-in actor. Neither struct is nil, so those configurations read every user as confirmed.

This issue affects ash_authentication: from 4.3.8 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Insufficient Session Expiration vulnerability in team-alembic AshAuthentication and AshAuthentication Phoenix allows a revoked session to remain fully authenticated.

A resource configured with session_identifier :jti and require_token_presence_for_authentication? disabled stores its session value as <jti>:<subject>. The jti is there so that signing out can revoke that one session. Neither reader consults it: AshAuthentication.Plug.Helpers.authenticate_resource_from_session/4 and AshAuthentication.Phoenix.LiveSession.on_mount/4 both split the value with split_identifier/2, discard the jti and pass the bare subject to AshAuthentication.subject_to_user/3, which reloads the record. The token-presence branch of each function does check its token, calling AshAuthentication.TokenResource.Actions.get_token/3 with the jti and the purpose user. Because the revocation record is never read, neither its revoked state nor its expiry constrains the session, so a session captured before sign-out keeps working.

This issue affects ash_authentication: from 4.9.1 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14; ash_authentication_phoenix: from 2.10.0 before 2.17.4 and from 3.0.0-rc.0 before 3.0.0-rc.11.

Summary

Use of HTTP Request With Sensitive Query String vulnerability in team-alembic AshAuthenticationPhoenix allows someone able to read access logs, proxy logs or browser history to recover a single-use sign-in token and authenticate as its owner.

After a successful password sign-in, AshAuthentication.Phoenix.Components.Password.SignInForm builds the sign_in_with_token path with the freshly issued user.__metadata__.token as a query parameter and redirects the browser to it with a GET. The token therefore travels in the request line, where web servers, reverse proxies, request telemetry and the browser's own history record it, all of which outlive the request and are ordinarily less protected than session storage. The redirect destination is restricted to a local path, so this is not an open redirect; the exposure is the retention of a live credential.

This issue affects ash_authentication_phoenix: from 1.7.0 before 2.17.4 and from 3.0.0-rc.0 before 3.0.0-rc.11; ash_authentication: from 3.10.5 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Improper Authentication vulnerability in team-alembic AshAuthentication allows an attacker holding a sign-in token for one authenticated resource to be signed in as a user of a different resource.

AshAuthentication.Strategy.Password.SignInWithTokenPreparation.extract_primary_keys_from_subject/2 parses the JWT sub claim (for example user?id=1) with URI.parse/1 and keeps only its query string, discarding the path segment that names the subject the token was issued for. Nothing else restores that binding: AshAuthentication.Jwt.verify/3 checks the signature, exp, nbf, jti and the library-version claims, the purpose check only requires sign_in, and the remaining comparison is over primary-key field names, which are identical across resources. The WebAuthn sign-in and remember-me preparations carry copies of the same helper and drop the path in the same way. The magic link sign-in path pins the subject name against the resource and is not affected.

This issue affects ash_authentication: from 3.10.5 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Improper Verification of Cryptographic Signature vulnerability in team-alembic AshAuthentication allows a caller of the token revocation action to neutralise a revocation or write arbitrary rows into the token resource.

AshAuthentication.TokenResource.RevokeTokenChange.change/3 reads the :token argument and decodes it with AshAuthentication.Jwt.peek/1, which delegates to Joken.peek_claims/1 and performs no signature check, unlike Jwt.verify/4. The jti, exp and sub claims it returns are written straight onto the revocation record, guarded only by byte_size(token) > 0. Because expires_at derives from the attacker-chosen exp, a forged copy of a genuine token that keeps the real jti but backdates exp yields a revocation row that is already expired: expunge_expired removes it and the genuine token passes revoked? again. Arbitrary jti and sub values can be inserted the same way.

This issue affects ash_authentication: from 0.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Improper Output Neutralization for Logs vulnerability in team-alembic AshAuthentication allows an unauthenticated attacker to forge application log entries by submitting a password reset identity containing newlines or control characters.

AshAuthentication.Strategy.Password.RequestPasswordReset.run/3 interpolates the identity argument, the email or username taken straight from the reset request, into its Logger.warning/1 heredocs without escaping, truncating or type-restricting it. The resource logged beside it is passed through inspect/1, which would have neutralized the value. A newline in the identity therefore ends the log record, and everything after it is written as a line of its own, so an attacker chooses the severity tag and the content of entries that appear to have come from the application.

This issue affects ash_authentication: from 4.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Insufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 state value to replay the callback and sign that victim into an attacker-controlled account.

AshAuthentication.Strategy.OAuth2.Plug.callback/2 clears the stored session_params through a rebinding step inside its with chain, conn <- delete_session(conn, session_key). Elixir evaluates the else block in the scope enclosing the with, so every failure path (the provider returning ?error=access_denied, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches store_authentication_result/2 holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry.

This issue affects ash_authentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in team-alembic AshAuthentication allows an attacker holding a leaked magic link to replay its single-use token and authenticate as the target subject. A magic link configured with single_use_token?, which is the default, is meant to be redeemable exactly once, but nothing serialises the token's validity check against its consumption, so concurrent redemptions of one token all succeed and each yields a full user token.

Sign-in verifies the JWT with Jwt.verify/4 and revokes it only afterwards: AshAuthentication.Strategy.MagicLink.SignInPreparation revokes in a Query.after_action callback, and AshAuthentication.Strategy.MagicLink.SignInChange in an after_transaction hook that runs once the sign-in has already committed. AshAuthentication.TokenResource.Actions.revoke/3 writes the revocation as an upsert, so a concurrent duplicate revocation silently succeeds instead of conflicting and no request ever loses the race.

This issue affects ash_authentication: from 3.9.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Authorization Bypass Through User-Controlled Key vulnerability in team-alembic AshAuthentication allows an authenticated attacker to overwrite and confirm another user's email address, and so take over that account. A confirmation token issued to one user is accepted on any other user's record.

AshAuthentication.AddOn.Confirmation.ConfirmChange verifies the token's signature and its act claim, then applies the changes stored against that token to whichever record the changeset targets, never comparing the sub claim against changeset.data. An attacker who registers an account and changes their own email replays the resulting token against a victim's record id, writing in their own address with force_change_attributes/2 and stamping confirmed_at, after which an ordinary password reset yields the account. The library's own confirmation flow is unaffected, because AshAuthentication.AddOn.Confirmation.Actions.confirm/3 resolves sub to a user and targets that record.

This issue affects ash_authentication: from 0.5.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Inefficient Algorithmic Complexity vulnerability in team-alembic AshAuthentication allows an unauthenticated attacker to exhaust CPU and memory via an oversized base62 segment in a submitted API key.

AshAuthentication.Base.decode62/1 in lib/ash_authentication/base.ex splits its argument into one binary per character and folds it with charval62/2, which recomputes Integer.pow(62, index) at every position instead of accumulating by Horner's method, so cost grows roughly cubically in the input length. bindecode62/1 in the same module is quadratic through Integer.undigits/2 and Integer.digits/2. Neither function caps byte_size/1, and AshAuthentication.Strategy.ApiKey.SignInPreparation passes the underscore-separated segments of the submitted key straight into both, before any key lookup and without prior authentication. The surrounding rescue clauses catch exceptions, not CPU or memory exhaustion.

This issue affects ash_authentication: from 4.8.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Summary

Use of a One-Way Hash with a Predictable Salt vulnerability in team-alembic AshAuthentication allows readers of the audit store to recover the client IP addresses that the audit log add-on's :hash privacy mode is meant to pseudonymise.

AshAuthentication.AddOn.AuditLog.IpPrivacy.hash_ip/1 computes a single unkeyed :crypto.hash(:sha256, salt <> ip) and truncates the result to 16 hexadecimal characters. The salt is read from the :audit_log_ip_salt or :secret application config keys, and falls back to the constant "default-salt-change-in-production" published in the library source when neither is set, with nothing warning that the default is in use. The IPv4 space is only 2^32 values and SHA-256 is fast, so the whole hash table is precomputable and every stored value maps back to its source address. Truncating to 16 characters does not help, and even a configured salt leaves the hash cheap enough to enumerate once it leaks.

This issue affects ash_authentication: from 4.12.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

Configurations

Only applications that enable the audit_log add-on and set its ip_privacy mode to :hash store the affected value. Other modes (:none, :truncate, :exclude) do not reach hash_ip/1.

The complete break additionally requires the default salt, that is neither :audit_log_ip_salt nor :secret configured under the :ash_authentication application. This is the out-of-the-box state: no warning or error is raised when the hardcoded salt is in use.

Summary

Insertion of Sensitive Information into Log File vulnerability in team-alembic AshAuthentication allows disclosure of user password digests to readers of the audit store.

The audit_log add-on builds each entry's extra_data in AshAuthentication.AddOn.AuditLog.Auditor.build_extra_data/4, which takes :actor from the action callback context verbatim. Any audited action invoked with actor: set to a user record therefore deposits that record, including its hashed_password attribute, into the audit entry. The same module already collapses the audited identity to an opaque string via AshAuthentication.user_to_subject/1 and filters params against the strategy's configured allow-list, so the actor is the only stored value that reaches the audit store unfiltered. Marking the attribute sensitive?: true does not help, because that redacts inspect/1 output rather than JSON encoding or raw-term storage.

There is no attacker-controlled trigger and no network disclosure path: entries accumulate from ordinary authenticated activity, and an attacker's own requests deposit only their own digest. Exploitation requires independent read access to the audit store, such as database credentials, an audit role, a backup, or a log shipper, at which point the digests support offline password attack against every active account. Whether the material persists depends on the data layer, since raw-term stores keep it verbatim while a SQL store raises Protocol.UndefinedError and drops the entry unless the user resource derives Jason.Encoder.

This issue affects ash_authentication: from 4.12.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.2.

Summary

Improper Authentication vulnerability in team-alembic AshAuthentication allows purpose-limited JWTs to be replayed as full bearer API credentials when a resource uses stateless bearer-token verification.

The bearer-token authentication helper AshAuthentication.Plug.Helpers.retrieve_from_bearer/3 verifies an Authorization: Bearer JWT's signature and rejects tokens containing an act claim, but performs no check that the token's purpose claim equals user at the bearer boundary. When the resource is configured with require_token_presence_for_authentication?: false (the DSL default), the follow-on validate_token/3 helper returns {:ok, nil} without consulting the token resource, so no downstream check on purpose takes place either. As a result, any valid, non-expired JWT the library itself issued for a narrow, single-purpose flow (most notably the purpose: sign_in token that WebAuthn always emits during sign-in, and that the Password strategy emits when sign-in tokens are enabled) is accepted directly as a general-purpose bearer credential and resolves to a full current_user assignment.