cvedb.io
CVE-2021-41267
MEDIUM · CVSS 6.5
EPSS exploitation probability: 0%
Published 2021-11-24T19:15:07.737 · Last modified 2026-06-17T04:08:12.260

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.

Affected products

sensiolabs — symfony

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.