CVE-2026-92288 Lemonldap::NG::Portal versions from 2.20.0 before 2.21.6, from 2.22.0 before 2.23.4 for Perl allow unauthenticated OAuth2 token introspectio
Unauthenticated attackers can introspect OAuth2 tokens and read metadata, including user identifiers, by bypassing client secret verification for public Relying Parties.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-92288?
CVE-2026-92288 is a critical authentication bypass vulnerability, published on 25 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Lemonldap::NG::Portal versions from 2.20.0 before 2.21.6, from 2.22.0 before 2.23.4 for Perl allow unauthenticated OAuth2 token introspection because checkEndPointAuthenticationCredentials does not verify the client secret of a public Relying Party.
checkEndPointAuthenticationCredentials() skips the secret comparison for a Relying Party marked public and still returns the authentication method deduced from the request, client_secret_basic or client_secret_post. introspection() rejects a caller only when that method is missing or none, so a request carrying a public client_id and an arbitrary or empty secret passes the endpoint's authentication check.
An attacker who holds an access token and knows the client_id of any public Relying Party can confirm the token is active and read its metadata, including scope, audience, expiry and the sub claim. The sub claim is computed with the calling Relying Party's user identifier attribute, so an attacker can translate a user identifier from one Relying Party to another, defeating per-client and pseudonymous identifiers.
Weakness: CWE-1390
Which versions are affected by CVE-2026-92288?
How do I fix CVE-2026-92288?
Upgrade to a fixed version.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-92288 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-92288 exists.
Sources
Also known as DEBIAN-CVE-2026-92288, GHSA-pxfv-p3g7-3fw3, UBUNTU-CVE-2026-92288.