---
id: CVE-2026-92289
title: >-
  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 oidcRPMetaD…
summary: >-
  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 oidcRPMetaD…
severity: medium
cwe:
  - CWE-1390
product: Lemonldap-NG-Portal
affected:
  - Lemonldap-NG-Portal >= 2.23.0 < 2.23.4
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T03:16:58.973'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-92289'
references:
  - url: 'https://gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/releases/v2.23.4'
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'https://gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/work_items/3719'
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'http://www.openwall.com/lists/oss-security/2026/09/25/2'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92289.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-92289'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-92289'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ingestedAt: '2026-09-25T00:56:54.274Z'
vendor: Red Hat
cvss: 6.8
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N'
cvssSource: vendor
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · updated 2026-09-25 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-92289.json)