CVE-2021-41267: Symfony/http kernel Webcache Poisoning Vulnerability
MODERATECVE-2021-41267 is a MODERATE (CVSS 6.5) webcache poisoning vulnerability (CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')) affecting Symfony/http kernel libraries in the Packagist ecosystem. The issue involves webcache poisoning in symfony/http-kernel. Remediation is available by upgrading affected packages to version 5.3.12.
CVE-2021-41267 at a Glance
Security Impact
CVSS: 6.5
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N).
How to Fix CVE-2021-41267
To remediate this vulnerability, upgrade all affected Symfony/http kernel dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade symfony/http-kernel to 5.3.12Upgrade symfony/symfony to 5.3.12Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for symfony/http-kernelHow to Check if You Are Affected
To determine whether your application is affected by CVE-2021-41267, inspect your project dependencies for Symfony/http kernel:
inspect dependencies for symfony/http-kernelAnalyze the terminal output to locate any version of Symfony/http kernel in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.3.12), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling'), where the product acts as an intermediary http agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed http requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination. In Symfony/http kernel, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2021-41267 Affected Symfony/http kernel Versions
2 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
symfony/http-kernel
|
Packagist |
≥ 5.2.0
< 5.3.12
|
5.3.12
|
|
symfony/symfony
|
Packagist |
≥ 5.2.0
< 5.3.12
|
5.3.12
|
References
Frequently Asked Questions
What is CVE-2021-41267?
Which Symfony/http kernel versions are affected?
What version fixes CVE-2021-41267?
Is symfony/http-kernel affected?
Is symfony/symfony affected?
What is the CVSS score of CVE-2021-41267?
What CWE is associated with CVE-2021-41267?
How can I check Packagist dependencies for CVE-2021-41267?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-q3j3-w37x-hq2q",
"modified" : "2024-02-05T11:13:47Z",
"published" : "2021-11-24T20:04:25Z",
"aliases" : [ "CVE-2021-41267" ],
"summary" : "Webcache Poisoning in symfony/http-kernel",
"details" : "Description\n-----------\n\nWhen 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. \n\nIn 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.\n\nResolution\n----------\n\nSymfony now ensures that the `X-Forwarded-Prefix` HTTP header is not forwarded to sub-requests when it is not trusted.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487) for branch 5.3.\n\nCredits\n-------\n\nWe would like to thank Soner Sayakci for reporting the issue and Jérémy Derussé for fixing the issue.\n",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Packagist",
"name" : "symfony/http-kernel"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "5.2.0"
}, {
"fixed" : "5.3.12"
} ]
} ]
}, {
"package" : {
"ecosystem" : "Packagist",
"name" : "symfony/symfony"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "5.2.0"
}, {
"fixed" : "5.3.12"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/symfony/symfony/security/advisories/GHSA-q3j3-w37x-hq2q"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-41267"
}, {
"type" : "WEB",
"url" : "https://github.com/symfony/symfony/pull/44243"
}, {
"type" : "WEB",
"url" : "https://github.com/symfony/symfony/commit/95dcf51682029e89450aee86267e3d553aa7c487"
}, {
"type" : "WEB",
"url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/http-kernel/CVE-2021-41267.yaml"
}, {
"type" : "WEB",
"url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2021-41267.yaml"
}, {
"type" : "WEB",
"url" : "https://github.com/symfony/symfony/releases/tag/v5.3.12"
}, {
"type" : "WEB",
"url" : "https://symfony.com/cve-2021-41267"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-444" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2021-11-24T19:58:05Z",
"nvd_published_at" : "2021-11-24T19:15:00Z"
}
}