team-alembic ash_authentication up to 4.14.9/5.0.0-rc.13 OAuth2 User Resolver improper authentication

Summaryinfo

A vulnerability labeled as critical has been found in team-alembic ash_authentication up to 4.14.9/5.0.0-rc.13. This vulnerability affects the function AshAuthentication.Strategy.OAuth2.UserResolver.resolve of the component OAuth2 User Resolver. Executing a manipulation can lead to improper authentication. This vulnerability is handled as CVE-2026-88952. The attack can be executed remotely. There is not any exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as critical was found in team-alembic ash_authentication up to 4.14.9/5.0.0-rc.13. This vulnerability affects the function AshAuthentication.Strategy.OAuth2.UserResolver.resolve of the component OAuth2 User Resolver. The manipulation with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2026-88952 since 09/16/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit.

Upgrading to version 4.15.0 or 5.0.0-rc.14 eliminates this vulnerability.

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Productinfo

Vendor

• team-alembic

Name

• ash_authentication

Version

• 4.14.0
• 4.14.1
• 4.14.2
• 4.14.3
• 4.14.4
• 4.14.5
• 4.14.6
• 4.14.7
• 4.14.8
• 4.14.9
• 5.0.0-rc.0
• 5.0.0-rc.1
• 5.0.0-rc.2
• 5.0.0-rc.3
• 5.0.0-rc.4
• 5.0.0-rc.5
• 5.0.0-rc.6
• 5.0.0-rc.7
• 5.0.0-rc.8
• 5.0.0-rc.9
• 5.0.0-rc.10
• 5.0.0-rc.11
• 5.0.0-rc.12
• 5.0.0-rc.13

Website

• Product: https://github.com/team-alembic/ash_authentication/

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