🛡️ CVE-2021-41267 — symfony

🟡 CVSS 5.0 — Medium ✅ No Known Exploit OSV
5.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Webcache Poisoning in symfony/http-kernel

Description

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When 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.

In 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.

Resolution

----------

Symfony now ensures that the X-Forwarded-Prefix HTTP header is not forwarded to sub-requests when it is not trusted.

The patch for this issue is available [here](https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487) for branch 5.3.

Credits

-------

We would like to thank Soner Sayakci for reporting the issue and Jérémy Derussé for fixing the issue.

Affected software

CVE-2021-41267 is recorded against 3 packages.

  • symfony
  • symfony/http-kernel (from 5.2.0 up to 5.3.12)
  • symfony/symfony (from 5.2.0 up to 5.3.12)

Timeline and source

Published on 6 March 2024. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Web)
github.com (Web)
github.com (Web)
github.com (Web)

CVE-2021-41267 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity MEDIUM
CVSS Score 5.0
CVSS Vector N/A
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2024-03-06
Updated 2026-08-12
Modified 2024-03-06
Fix URL N/A

Affected Packages

Software From version Fixed in
symfony — —
symfony/http-kernel 5.2.0 5.3.12
symfony/symfony 5.2.0 5.3.12

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