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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-92288
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-25 01:16:48 UTC
Updated2026-09-25 03:16:58 UTC
DescriptionLemonldap::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.

Risk And Classification

Problem Types: CWE-1390 | CWE-1390 CWE-1390 Weak Authentication

References

ReferenceSourceLinkTags
gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/work_items/3721 9b29abf9-4ab0-4765-b253-1875cd9b441e gitlab.ow2.org
gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/work_items/3719 9b29abf9-4ab0-4765-b253-1875cd9b441e gitlab.ow2.org
gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/releases/v2.23.4 9b29abf9-4ab0-4765-b253-1875cd9b441e gitlab.ow2.org
www.openwall.com/lists/oss-security/2026/09/25/1 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/releases/v2.21.6 9b29abf9-4ab0-4765-b253-1875cd9b441e gitlab.ow2.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

Solutions

CNA: Upgrade to Lemonldap-NG-Portal 2.21.6 or 2.23.4 or later. Only 2.23.4 is on CPAN; the 2.21.6 LTS release is available from https://lemonldap-ng.org/download.html.

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