CVE-2026-88952

published 2026-09-17

CVE-2026-88952: Improper Authentication vulnerability in team-alembic AshAuthentication allows an attacker to be signed in as another user by linking an OAuth2 identity to an…

Priority P2 62 critical 9.1 CVSS 4.0

AV N AC L AT P PR N UI N VC H VI H VA N SC N SI N SA N E X CR X IR X AR X MAV X MAC X MAT X MPR X MUI X MVC X MVI X MVA X MSC X MSI X MSA X S X AU X R X V X RE X U X

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.

Affected

4 ranges

Vendor	Product	Version range	Fixed in
team-alembic	ash_authentication	>= 4.14.0 < 4.15.0	4.15.0
team-alembic	ash_authentication	>= 42edcd8ebb13fafbb168f12591d7518ce0611fec < *	*
team-alembic	ash_authentication	>= 5.0.0-rc.10 < 5.0.0-rc.14	5.0.0-rc.14
team-alembic	ash_authentication	>= 64530644f9b37ebb76ca14aeb83a77597a0034b7 < *	*

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CWE-287