CVE-2026-80218
Sign-in token minted for one resource accepted by another in AshAuthentication
- State
- Published
- Severity
- 7.6 High
- Published
- Sep 17, 2026
- Updated
- Sep 17, 2026
- Reserved
- Sep 11, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 7.6 High | 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 | EEF |
Weaknesses
- CWE-287 Improper Authentication
Affected Products
| Product | Versions |
|---|---|
ash_authenticationteam-alembic |
|
ash_authenticationteam-alembic |
|
References
- https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-3pr8-f99q-86hpvendor-advisoryrelated
- EEF CNA record for CVE-2026-80218related
- OSV record EEF-CVE-2026-80218related
- Introducing commit eca8cad in team-alembic/ash_authenticationrelated
- Fix commit 2640e18 in team-alembic/ash_authenticationpatch
- Fix commit 7baac24 in team-alembic/ash_authenticationpatch
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