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.
The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
| Link | Tags |
|---|---|
| https://github.com/symfony/symfony/pull/44243 | third party advisory patch |
| https://github.com/symfony/symfony/releases/tag/v5.3.12 | third party advisory release notes |
| https://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2q | third party advisory patch |
| https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487 | third party advisory patch |