CVE-2026-88952

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.

Affected Software

VendorProductVersion RangeStatus
team-alembicash_authentication4.14.0 < 4.15.0affected
team-alembicash_authentication5.0.0-rc.10 < 5.0.0-rc.14affected
team-alembicash_authentication64530644f9b37ebb76ca14aeb83a77597a0034b7 < *affected
team-alembicash_authentication42edcd8ebb13fafbb168f12591d7518ce0611fec < *affected

Weaknesses

  • CWE-287: CWE-287 Improper Authentication

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.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: total

References