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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| team-alembic | ash_authentication | 3.10.5 – < 4.15.0, 5.0.0-rc.0 – < 5.0.0-rc.14 | 4.15.0 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Hex | ash_authentication | >= 3.10.5, < 4.15.0 · >= 5.0.0-rc.0, < 5.0.0-rc.14 | 4.15.0, 5.0.0-rc.14 | EEF-CVE-2026-80218 |
References
- https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-3pr8-f99q-86hp vendor-advisory related
- EEF CNA record for CVE-2026-80218 related
- OSV record EEF-CVE-2026-80218 related
- Introducing commit eca8cad in team-alembic/ash_authentication related
- Fix commit 2640e18 in team-alembic/ash_authentication patch
- Fix commit 7baac24 in team-alembic/ash_authentication patch