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

{
  "id": "dc6033d8455aa879be5c08cf058f6263a02147ff44205c3f9d806780bfdadb64",
  "url": "https://osv.dev/vulnerability/CVE-2026-92289",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "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",
    "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 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.",
    "evidence": "osv:CVE-2026-92289",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-92289",
      "aliases": [
        "CVE-2026-92289"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://gitlab.ow2.org/lemonldap-ng/lemonldap-ng",
              "type": "GIT",
              "events": [
                {
                  "introduced": "b33d2e2346596048fb83d4d98bb758b4e1b8e07d"
                },
                {
                  "fixed": "6602ae87a262e28539d54454ec99622c75141cb5"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "2.23.0"
                      },
                      {
                        "fixed": "2.23.4"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "2.23.0"
                      },
                      {
                        "fixed": "2.23.4"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.23.3",
            "v2.23.2",
            "v2.23.1",
            "v2.23.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-92289.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:36.798155008Z",
      "provider": "osv",
      "references": [
        "https://cpan.org/modules",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/92xxx/CVE-2026-92289.json",
        "https://gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/releases/v2.23.4",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-92289",
        "https://gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/work_items/3719",
        "https://gitlab.ow2.org/lemonldap-ng/lemonldap-ng"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-1390"
        ],
        "cna_assigner": "CPANSec",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/92xxx/CVE-2026-92289.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-92289",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 504304,
  "published_at": "2026-09-25T00:15:49.826+00:00"
}