CVE-2026-41671 Admidio: OIDC Token Introspection Endpoint Returns Active for All Tokens Without Validation
Admidio's OIDC introspection endpoint falsely validates all tokens, allowing attackers to bypass authentication and gain unauthorized access.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-41671?
CVE-2026-41671 is a medium-severity authentication bypass vulnerability in admidio, published on 7 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Admidio is an open-source user management solution. Prior to version 5.0.9, the OIDC token introspection endpoint (/modules/sso/index.php/oidc/introspect) always returns {"active": true} for every request, regardless of whether a valid token is provided, whether the token is expired, revoked, or completely fabricated. The endpoint performs no authentication of the calling resource server and no validation of the submitted token. Any resource server that relies on this introspection endpoint to validate access tokens will accept all requests as authorized, enabling complete authentication bypass. Additionally, the OIDC token revocation endpoint (/oidc/revoke) returns {"revoked": true} without actually revoking any token, preventing resource servers from invalidating compromised credentials. This issue has been patched in version 5.0.9.
Weakness: CWE-287
Which versions are affected by CVE-2026-41671?
2 open source packages ship an affected version, including admidio/admidio.
| Package | Affected | Fixed in |
|---|---|---|
admidio/admidio Packagist | All versions | 5.0.9 |
admidio/admidio Packagist | All versions | 5.0.9 |
How do I fix CVE-2026-41671?
Upgrade admidio/admidio to 5.0.9 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-41671 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41671 exists.
Sources
Also known as GHSA-9xx5-cv6j-x533.