HOME VULNERABILITIESCVE-2021-41267

MEDIUM

CVE-2021-41267

CWE-444Published: November 24, 2021· Updated: Jun 17, 2026

6.5

CVSS v3.1

Official 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.

Technical Analysis

CVE-2021-41267 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in full integrity compromise (data manipulation), with a CVSS base score of 6.5.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges Req.None

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Affected Vendors & Products

sensiolabs1 product(s)

symfony

Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time

Offensive Security exploit database

GitHub PoC Search

Community PoC repositories

Rapid7 / Metasploit

Metasploit module search

Security advisories & exploits

Official NIST entry

CVE Program entry

External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487

PATCHhttps://github.com/symfony/symfony/pull/44243

PATCHhttps://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2q

PATCHhttps://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487

PATCHhttps://github.com/symfony/symfony/pull/44243

PATCHhttps://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2q

ADVISORYhttps://github.com/symfony/symfony/releases/tag/v5.3.12

ADVISORYhttps://github.com/symfony/symfony/releases/tag/v5.3.12

All References (8)

→

https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487Patch · Third Party Advisory

→

https://github.com/symfony/symfony/pull/44243Patch · Third Party Advisory

→

https://github.com/symfony/symfony/releases/tag/v5.3.12Release Notes · Third Party Advisory

→

https://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2qPatch · Third Party Advisory

→

https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487Patch · Third Party Advisory

→

https://github.com/symfony/symfony/pull/44243Patch · Third Party Advisory

→

https://github.com/symfony/symfony/releases/tag/v5.3.12Release Notes · Third Party Advisory

→

https://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2qPatch · Third Party Advisory

Quick Facts

CVE IDCVE-2021-41267

CVSS Score6.5 / 10

SeverityMEDIUM

WeaknessCWE-444

CISA KEVNo

Affected1 vendor(s)

PublishedNov 24, 2021

Related CVEs (CWE-444)

Recommended Actions

→Apply vendor patches immediately
→Monitor CVE-2021-41267 in threat intel feeds
→Review IDS/IPS signatures for exploitation attempts

Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.

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