Security advisory

{
  "id": "a6af2723742928cbcee2af5838b38833d64223a30a5066b35c805e3ea56a9d44",
  "url": "https://osv.dev/vulnerability/CVE-2021-41267",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-41267",
    "summary": "Symfony/Http-Kernel is the HTTP kernel component for Symfony, a PHP framework for web and console applications and a set of reusable PHP components. Headers that are not part of the \"trusted_headers\" allowed list are ignored and protect users from \"Cache poisoning\" attacks. In Symfony 5.2, maintainers added support for the `X-Forwarded-Prefix` headers, but this header was accessible in SubRequest, even if it was not part of the \"trusted_headers\" allowed list. An attacker could leverage this opportunity to forge requests containing a `X-Forwarded-Prefix` header, leading to a web cache poisoning issue. Versions 5.3.12 and later have a patch to ensure that the `X-Forwarded-Prefix` header is not forwarded to subrequests when it is not trusted.",
    "evidence": "osv:CVE-2021-41267",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-41267",
      "aliases": [
        "BIT-symfony-2021-41267",
        "CVE-2021-41267",
        "GHSA-q3j3-w37x-hq2q"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/symfony/symfony",
              "type": "GIT",
              "events": [
                {
                  "introduced": "8b51547061b29081803eb9fdf9b02cf80a1e1a74"
                },
                {
                  "fixed": "256c34a45b79fdc6276a8c941a1656713ee1ffec"
                },
                {
                  "fixed": "95dcf51682029e89450aee86267e3d553aa7c487"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:sensiolabs:symfony:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "5.2.0"
                      },
                      {
                        "fixed": "5.3.12"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "95dcf51682029e89450aee86267e3d553aa7c487"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "256c34a45b79fdc6276a8c941a1656713ee1ffec"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v5.3.12"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-41267.json"
          }
        }
      ],
      "modified": "2026-10-24T10:50:42.852849150Z",
      "provider": "osv",
      "references": [
        "https://github.com/symfony/symfony/releases/tag/v5.3.12",
        "https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487",
        "https://github.com/symfony/symfony/pull/44243",
        "https://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2q"
      ],
      "provider_metadata": {
        "unresolved_ranges": [
          {
            "cpes": [
              "cpe:2.3:a:sensiolabs:symfony:*:*:*:*:*:*:*:*"
            ],
            "vendor_product": "sensiolabs:symfony",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "5.2.0"
                  },
                  {
                    "fixed": "5.3.12"
                  }
                ],
                "source": "CPE_RANGE"
              }
            ]
          }
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2021-41267",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 442519,
  "published_at": "2021-11-24T19:15:07.737+00:00"
}