Vulnerability Description
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.
Related Weaknesses (CWE)
References
- https://cna.erlef.org/cves/CVE-2026-80218.html
- https://github.com/team-alembic/ash_authentication/commit/2640e1872e1fef4e4606e6
- https://github.com/team-alembic/ash_authentication/commit/7baac243ca651eee127a84
- https://github.com/team-alembic/ash_authentication/commit/eca8cadea0f1595ed2c10a
- https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-3pr8
- https://osv.dev/vulnerability/EEF-CVE-2026-80218
FAQ
What is CVE-2026-80218?
CVE-2026-80218 is a documented vulnerability. 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. As...
How severe is CVE-2026-80218?
CVSS scoring is not yet available for CVE-2026-80218. Check NVD for updates.
Is there a patch for CVE-2026-80218?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.