CVE-2026-86688 is a session fixation vulnerability in the team-alembic ash_authentication library. The flaw allows an attacker who can plant a session identifier in a victim's browser to maintain an authenticated session after the victim logs in. This occurs because the library writes the authenticated subject into the existing session without renewing the session identifier, allowing the original identifier to persist through login and logout cycles. This affects versions from 0.2.0 up to but not including 4.15.0, and from 5.0.0-rc.0 up to but not including 5.0.0-rc.14.
CVE-2026-76949 is an authentication bypass vulnerability in the team-alembic ash_authentication library. It allows an attacker who can plant a remember-me cookie in a victim's browser to replace the victim's authenticated session with the attacker's session. This occurs due to inconsistent session key handling in the remember-me sign-in logic, causing the system to honor the attacker's cookie even when the victim has an active authenticated session. The vulnerability affects versions from 4.10.0 up to but not including 4.15.0, and from 5.0.0-rc.0 up to but not including 5.0.0-rc.14.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
CVE-2026-65633 is an improper authentication vulnerability in the ash_authentication library by team-alembic. It allows purpose-limited JWT tokens, such as sign_in tokens, to be replayed as full bearer API credentials when stateless bearer-token verification is used without strict purpose checks. This bypasses intended one-time-use and revocation semantics, enabling an attacker with a valid sign_in token to authenticate as the token's subject. The issue affects versions from 3.10.5 before 4.14.2 and from 5.0.0-rc.0 before 5.0.0-rc.13. Resources configured with require_token_presence_for_authentication?: true or using session-based authentication are not affected.
CVE-2026-66882 is a reflected cross-site scripting (XSS) vulnerability in the team-alembic ash_authentication library. It occurs when certain parameters are embedded directly into HTML form inputs without proper escaping, allowing an attacker to inject malicious scripts. This affects the confirmation and magic link interaction forms when require_interaction? is set to true. An unauthenticated attacker can craft a URL that triggers script execution in the context of the vulnerable application, potentially exposing cookies and session data. The vulnerability affects ash_authentication versions from 4.8.0 up to but not including 4.14.2, and from 5.0.0-rc.0 up to but not including 5.0.0-rc.13. The CVSS 4.0 base score is 2.1, indicating low severity.
CVE-2026-49757 is a critical authentication bypass vulnerability in team-alembic's ash_authentication library affecting versions from 0.1.0 before 4.14.0 and from 5.0.0-rc.0 before 5.0.0-rc.10. The flaw allows an attacker to take over local user accounts via OAuth2/OIDC sign-in by matching users based on email rather than the required unique OpenID Connect iss/sub claims. This enables an unauthenticated attacker who can register an OAuth provider account with a victim's email to impersonate that victim and gain their privileges. The issue arises because email addresses, including unverified or reused ones, were used as unique identifiers instead of the stable iss/sub combination. The fix involves resolving users by the (strategy, sub) identity and only linking by email if the email_verified claim is trusted.