CVE-2026-92289 Lemonldap::NG::Portal versions from 2.23.0 before 2.23.4 for Perl allow a PKCE bypass for public Relying Parties in "PKCE or secret" mode be
Attackers can bypass PKCE protections in LemonLDAP::NG Portal to exchange intercepted authorization codes for user tokens, leading to account takeover.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-92289?
CVE-2026-92289 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 2.23.0 before 2.23.4 for Perl allow a PKCE bypass for public Relying Parties in "PKCE or secret" mode because checkEndPointAuthenticationCredentials does not verify the client secret.
With oidcRPMetaDataOptionsRequirePKCE set to 2, the authorization endpoint issues a code even when the request carries no code_challenge, and token() admits the exchange as long as a challenge was stored or an authentication method was returned for the caller. checkEndPointAuthenticationCredentials() skips the secret comparison for a Relying Party marked public and still returns the method deduced from the request, so any Basic or form credential satisfies the secret branch. validatePKCEChallenge() then passes, because neither a challenge nor a verifier is present.
An attacker who intercepts an authorization code issued to a public Relying Party can exchange it for the user's access, ID and refresh tokens by replaying the client_id with an arbitrary secret, which is the attack PKCE prevents. Dynamic client registration creates every Relying Party in this mode.
Weakness: CWE-1390
Which versions are affected by CVE-2026-92289?
How do I fix CVE-2026-92289?
Upgrade to a fixed version.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-92289 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-92289 exists.
Sources
Also known as DEBIAN-CVE-2026-92289, GHSA-vw4x-93xp-f6f3, UBUNTU-CVE-2026-92289.