{"cve":"CVE-2021-41267","nvd":{"published":"2021-11-24T19:15:07.737","modified":"2026-06-17T04:08:12.260","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","score":6.5},"cwes":["CWE-444"],"references":["https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487","https://github.com/symfony/symfony/pull/44243","https://github.com/symfony/symfony/releases/tag/v5.3.12","https://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2q","https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487"],"products":["sensiolabs:symfony"],"source":"nvd","synced_at":"2026-10-19T21:25:41.256909649+00:00"},"epss":{"cve":"CVE-2021-41267","score":0.0128,"percentile":0.70019,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}