{
  "canonical_id": "symfony--CVE-2021-41267",
  "system_id": "symfony",
  "display_name": "Symfony",
  "category": "frameworks",
  "advisory_mode": "core",
  "title": "Webcache Poisoning in symfony/http-kernel",
  "summary": "Description\n-----------\n\nWhen a Symfony application is running behind a proxy or a load-balancer, you can tell Symfony to look for the `X-Forwarded-*` HTTP headers. HTTP headers that are not part of the \"trusted_headers\" allowed list are ignored and protect you from \"Cache poisoning\" attacks. \n\nIn Symfony 5.2, we've added support for the `X-Forwarded-Prefix` header, but this header was accessible in sub-requests, 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` HTTP header, leading to a web cache poisoning issue.\n\nResolution\n----------\n\nSymfony now ensures that the `X-Forwarded-Prefix` HTTP header is not forwarded to sub-requests when it is not trusted.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487) for branch 5.3.\n\nCredits\n-------\n\nWe would like to thank Soner Sayakci for reporting the issue and J\u00e9r\u00e9my Deruss\u00e9 for fixing the issue.\n",
  "published_at": "2021-11-24T20:04:25Z",
  "updated_at": "2026-03-13T22:00:11.423907Z",
  "severity": "low",
  "cvss_score": 3.1,
  "exploit_status": "unknown",
  "source_confidence": "official",
  "official_source_url": "https://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2q",
  "secondary_source_urls": [
    "https://nvd.nist.gov/vuln/detail/CVE-2021-41267",
    "https://github.com/symfony/symfony/pull/44243",
    "https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487",
    "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/http-kernel/CVE-2021-41267.yaml",
    "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2021-41267.yaml",
    "https://github.com/symfony/symfony/releases/tag/v5.3.12",
    "https://symfony.com/cve-2021-41267"
  ],
  "aliases": [
    "BIT-symfony-2021-41267",
    "CVE-2021-41267",
    "GHSA-q3j3-w37x-hq2q"
  ],
  "cve_ids": [
    "CVE-2021-41267"
  ],
  "ghsa_ids": [
    "GHSA-q3j3-w37x-hq2q"
  ],
  "osv_ids": [
    "GHSA-q3j3-w37x-hq2q"
  ],
  "affected_versions": [
    "v5.2.0",
    "v5.2.1",
    "v5.2.10",
    "v5.2.11",
    "v5.2.12",
    "v5.2.13",
    "v5.2.14",
    "v5.2.2",
    "v5.2.3",
    "v5.2.4",
    "v5.2.5",
    "v5.2.6",
    "v5.2.7",
    "v5.2.8",
    "v5.2.9",
    "v5.3.0",
    "v5.3.0-BETA1",
    "v5.3.0-BETA2",
    "v5.3.0-BETA3",
    "v5.3.0-BETA4",
    "introduced=5.2.0, fixed<5.3.12"
  ],
  "fixed_versions": [
    "5.3.12"
  ],
  "package_name": "symfony/symfony",
  "render_markdown": true,
  "case_path": "07-framework-security/frameworks/symfony/cases/symfony-cve-2021-41267.md",
  "secure_code_topics": [
    "xss-output-encoding",
    "authz-server-side-recheck",
    "path-traversal-guard",
    "proxy-trust-boundary"
  ],
  "status": "generated",
  "triage_reasons": [],
  "verification_status": "triage-manual",
  "verification_mode": "synthetic",
  "last_verified_at": null,
  "last_run_id": null,
  "evidence_bundle": null,
  "historical_status": null,
  "latest_status": null,
  "browser_evidence": {
    "required": false,
    "present": false,
    "refs": []
  },
  "repro_profile_id": "xss-generic",
  "artifact_mode": "synthetic",
  "blocked_reason": null,
  "metadata": {
    "source_names": [
      "OSV Symfony"
    ],
    "source_kinds": [
      "osv-batch"
    ],
    "candidate_count": 2
  }
}