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.
CVSS Details
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N Threat Intelligence
No active exploitation signals — not in CISA KEV and no EPSS score yet.
Weaknesses 1
Affected Products 1
| Vendor | Product | Version | Range |
|---|---|---|---|
| sensiolabs | symfony | * | ≥5.2.0 – <5.3.12 |
References 4
- github.com https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487
- github.com https://github.com/symfony/symfony/pull/44243
- github.com https://github.com/symfony/symfony/releases/tag/v5.3.12
- github.com https://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2q
Remediation
- github.com https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487
- github.com https://github.com/symfony/symfony/pull/44243
- github.com https://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2q