Vulnerability · Published Sep 17, 2026 · Assigned by EEF
CVE-2026-80218Sign-in token minted for one resource accepted by another in AshAuthentication
High 7.6
In plain English
A high-severity improper authentication in ash_authentication from team-alembic. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 51% of all known vulnerabilities).
Official 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 (as reported)
| Vendor | Product | Versions |
|---|---|---|
| team-alembic | ash_authentication | 3.10.5 – before 4.15.05.0.0-rc.0 – before 5.0.0-rc.14 |
| team-alembic | ash_authentication | eca8cadea0f1595ed2c10a0c177b1da9aa9e5269 – before * |
Weakness: CWE-287 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
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