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CVE-2021-41267

Published: 24 November 2021

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.

Priority

Medium

Cvss 3 Severity Score

6.5

Score breakdown

Status

Package Release Status
symfony
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(code not present)
focal Not vulnerable
(code not present)
hirsute Ignored
(end of life)
impish Ignored
(end of life)
jammy Needed

kinetic Ignored
(end of life, was needed)
lunar Ignored
(end of life, was needed)
mantic Needed

noble Needed

trusty Ignored
(end of standard support)
upstream Not vulnerable
(debian: Vulnerable code never in released version in unstable)
xenial Not vulnerable
(code not present)
Patches:
upstream: https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487

Severity score breakdown

Parameter Value
Base score 6.5
Attack vector Network
Attack complexity Low
Privileges required None
User interaction Required
Scope Unchanged
Confidentiality None
Integrity impact High
Availability impact None
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N