CVE-2021-41267
Webcache Poisoning in symfony/http-kernel
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.
How to fix CVE-2021-41267
To remediate CVE-2021-41267, upgrade the affected package to a fixed version below.
- —upgrade to 5.3.12 or later
- —upgrade to 5.3.12 or later
- —upgrade to 5.3.12 or later
Is CVE-2021-41267 being exploited?
Low — EPSS is 0.5%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- >= 5.2.0, < 5.3.12
- >= 5.2.0, < 5.3.12
- >= 5.2.0, < 5.3.12
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N |
References (8)
- ADVISORYnvd.nist.gov/vuln/detail/CVE-2021-41267
- WEBgithub.com/FriendsOfPHP/security-advisories/blob/master/symfony/http-kernel/CVE-2021-41267.yaml
- WEBgithub.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2021-41267.yaml
- WEBgithub.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487