CVE-2021-41267
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
Debian Fixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 0 |
| sid | Fixed | 0 |
| forky | Fixed | 0 |
| bullseye | Fixed | 0 |
| bookworm | Fixed | 0 |
Package impact
| Ecosystem | Package | Vulnerable | Fixed |
|---|---|---|---|
| Packagist | symfony/http-kernel | >=5.2.0,<5.3.12 | 5.3.12 |
| Packagist | symfony/symfony | >=5.2.0,<5.3.12 | 5.3.12 |
References
- https://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2q
- https://nvd.nist.gov/vuln/detail/CVE-2021-41267
- https://github.com/symfony/symfony/pull/44243
- https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/http-kernel/CVE-2021-41267.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2021-41267.yaml
- https://github.com/symfony/symfony/releases/tag/v5.3.12
- https://symfony.com/cve-2021-41267
- https://security-tracker.debian.org/tracker/CVE-2021-41267
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.