Security advisory

{
  "id": "a5a3b4ce62aa6c5c991857d504773f5d644eeb7951f879960606ec6f236ed90d",
  "url": "https://osv.dev/vulnerability/CVE-2021-39191",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-39191",
    "summary": "mod_auth_openidc is an authentication/authorization module for the Apache 2.x HTTP server that functions as an OpenID Connect Relying Party, authenticating users against an OpenID Connect Provider. In versions prior to 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the `target_link_uri` parameter. A patch in version 2.4.9.4 made it so that the `OIDCRedirectURLsAllowed` setting must be applied to the `target_link_uri` parameter. There are no known workarounds aside from upgrading to a patched version.",
    "evidence": "osv:CVE-2021-39191",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-39191",
      "aliases": [
        "CVE-2021-39191",
        "GHSA-2pgf-8h6h-gqg2"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/openidc/mod_auth_openidc",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "03e6bfb446f4e3f27c003d30d6a433e5dd8e2b3d"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:openidc:mod_auth_openidc:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.4.9.4"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "03e6bfb446f4e3f27c003d30d6a433e5dd8e2b3d"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "03e6bfb446f4e3f27c003d30d6a433e5dd8e2b3d"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v2.4.9.4"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.4.9.3",
            "v2.4.9.2",
            "v2.4.9.1",
            "v2.4.9",
            "v2.4.8.4",
            "v2.4.8.3",
            "v2.4.8.2",
            "v2.4.8.1",
            "v2.4.7.2",
            "v2.4.7.1",
            "v2.4.7",
            "v2.4.6",
            "v2.4.5",
            "v2.4.4.1",
            "v2.4.4",
            "v2.4.3",
            "v2.4.2.1",
            "v2.4.2",
            "v2.4.1",
            "v2.4.0.4",
            "v2.4.0.3",
            "v2.4.0.2",
            "v2.4.0.1",
            "v2.4.0",
            "v2.3.11",
            "2.3.11rc1",
            "v2.3.10.2",
            "v2.3.10.1",
            "v2.3.10",
            "v2.3.9",
            "v2.3.8",
            "v2.3.7",
            "v2.3.6",
            "v2.3.5",
            "v2.3.4",
            "v2.3.3",
            "v2.3.2",
            "v2.3.1",
            "v2.3.0",
            "v2.3.0rc3",
            "v2.3.0rc0",
            "v2.2.0",
            "v2.1.6",
            "v2.1.5",
            "v2.1.4",
            "v2.1.3",
            "v2.1.2",
            "v2.1.1",
            "v2.1.0",
            "v2.0.0",
            "v2.0.0rc4",
            "v2.0.0rc1",
            "v1.8.10",
            "v1.8.9",
            "v1.8.8",
            "v1.8.7",
            "v1.8.6",
            "v1.8.5",
            "v1.8.4",
            "v1.8.3",
            "v1.8.2",
            "v1.8.1",
            "v1.8.0",
            "v1.7.0",
            "v1.6.0",
            "v1.5.5",
            "v1.5.4",
            "v1.5.3",
            "v1.5.2",
            "v1.5.1",
            "v1.5"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-39191.json",
            "vanir_signatures": [
              {
                "id": "CVE-2021-39191-1d53a487",
                "digest": {
                  "length": 3326,
                  "function_hash": "255789951588007788344141961223198622431"
                },
                "source": "https://github.com/openidc/mod_auth_openidc/commit/03e6bfb446f4e3f27c003d30d6a433e5dd8e2b3d",
                "target": {
                  "file": "src/mod_auth_openidc.c",
                  "function": "oidc_handle_discovery_response"
                },
                "deprecated": false,
                "signature_type": "Function",
                "signature_version": "v1"
              }
            ],
            "vanir_signatures_modified": "2026-10-24T14:25:20Z"
          }
        }
      ],
      "modified": "2026-10-24T14:25:20.854363074Z",
      "provider": "osv",
      "references": [
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/32RGPW5LZDLDTB7MKZIGAHPSLFOUNWR5/",
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RHXO4O4G2UQS7X6OQJCVZKHZAQ7SAIFB/",
        "https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9.4",
        "https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-2pgf-8h6h-gqg2",
        "https://github.com/zmartzone/mod_auth_openidc/commit/03e6bfb446f4e3f27c003d30d6a433e5dd8e2b3d",
        "https://lists.debian.org/debian-lts-announce/2023/07/msg00020.html",
        "https://github.com/zmartzone/mod_auth_openidc/issues/672"
      ],
      "provider_metadata": {
        "unresolved_ranges": [
          {
            "cpes": [
              "cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*"
            ],
            "vendor_product": "debian:debian_linux",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "10.0"
                  },
                  {
                    "last_affected": "10.0"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          },
          {
            "cpes": [
              "cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*",
              "cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:*"
            ],
            "vendor_product": "fedoraproject:fedora",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "35"
                  },
                  {
                    "last_affected": "35"
                  },
                  {
                    "introduced": "36"
                  },
                  {
                    "last_affected": "36"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          }
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2021-39191",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 443759,
  "published_at": "2021-09-03T14:15:07.21+00:00"
}