{"id":"CVE-2026-88952","summary":"OAuth2 sign-in attached to an existing account without an email comparison in AshAuthentication","details":"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.\n\nAshAuthentication.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.\n\nThis 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.","aliases":["EEF-CVE-2026-88952","GHSA-wc6x-276q-jrf9"],"modified":"2026-09-23T03:47:32.319434150Z","published":"2026-09-17T14:15:19.506Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/88xxx/CVE-2026-88952.json","unresolved_ranges":[{"extracted_events":[{"introduced":"64530644f9b37ebb76ca14aeb83a77597a0034b7"},{"fixed":"*"},{"introduced":"42edcd8ebb13fafbb168f12591d7518ce0611fec"},{"fixed":"*"}],"source":"AFFECTED_FIELD"}],"cna_assigner":"EEF","cwe_ids":["CWE-287"]},"references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-88952.html"},{"type":"WEB","url":"https://github.com"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-88952"},{"type":"WEB","url":"https://repo.hex.pm"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/88xxx/CVE-2026-88952.json"},{"type":"ADVISORY","url":"https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-wc6x-276q-jrf9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-88952"},{"type":"FIX","url":"https://github.com/team-alembic/ash_authentication/commit/2bd630eef8b7c8ae1e90e8fd43ba12fbc7e256ba"},{"type":"FIX","url":"https://github.com/team-alembic/ash_authentication/commit/42edcd8ebb13fafbb168f12591d7518ce0611fec"},{"type":"FIX","url":"https://github.com/team-alembic/ash_authentication/commit/64530644f9b37ebb76ca14aeb83a77597a0034b7"},{"type":"FIX","url":"https://github.com/team-alembic/ash_authentication/commit/738bf9f32f2aa0d1bb92ce9ca5c2476cb5710459"},{"type":"PACKAGE","url":"https://github.com/team-alembic/ash_authentication"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/team-alembic/ash_authentication","events":[{"introduced":"8badd8f3d618fb864bda1b041c815f7925c35861"},{"fixed":"d6b2be35cf8f0b8ab84e7a934cfb0d91de0a3c17"},{"introduced":"8fa0d9823fbef04aaab517e7ea0f4b17976f1502"},{"fixed":"fea75958a081ed337ceb578396174039694c48df"},{"fixed":"2bd630eef8b7c8ae1e90e8fd43ba12fbc7e256ba"},{"fixed":"42edcd8ebb13fafbb168f12591d7518ce0611fec"},{"fixed":"64530644f9b37ebb76ca14aeb83a77597a0034b7"},{"fixed":"738bf9f32f2aa0d1bb92ce9ca5c2476cb5710459"}],"database_specific":{"extracted_events":[{"introduced":"4.14.0"},{"fixed":"4.15.0"},{"introduced":"5.0.0-rc.10"},{"fixed":"5.0.0-rc.14"}],"source":["DESCRIPTION","REFERENCES"]}}],"versions":["v4.14.2","v5.0.0-rc.13","v4.14.1","v5.0.0-rc.12","v5.0.0-rc.11","v5.0.0-rc.10","v4.14.0"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-88952.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}