Symfony Allows URI Restrictions Bypass Via Double-Encoded String

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

• CVE-2012-6431: 1.88% estimated exploitation activity in the next 30 days; percentile 79.44 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

On the Symfony 2.0.x version, there's a security issue that allows access to routes protected by a firewall even when the user is not logged in. Both the Routing component and the Security component uses the path returned by getPathInfo() to match a Request. The getPathInfo() returns a decoded path, but the Routing component (Symfony\Component\Routing\Matcher\UrlMatcher) decodes the path a second time; whereas the Security component, Symfony\Component\HttpFoundation\RequestMatcher, does not. This difference causes Symfony 2.0 to be vulnerable to double encoding attacks.

Published by the source

17 May 2022, 05:17 UTC

Last modified by the source

6 Feb 2024, 16:01 UTC

Source last checked

26 Oct 2026, 14:15 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-83c3-qx27-2rwr

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# Patch Next advisory brief: CVE-2012-6431

Advisory: Symfony Allows URI Restrictions Bypass Via Double-Encoded String
IDs: CVE-2012-6431, GHSA-83c3-qx27-2rwr
Record: https://patchnext.com/advisories/cve-2012-6431 (revision 1, source checked 26 Oct 2026, 14:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: symfony/symfony 2.0.19; symfony/routing 2.0.19; symfony/security 2.0.19; symfony/http-foundation 2.0.19. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist symfony/symfony: affected >= 2.0.0, < 2.0.19; fixed in 2.0.19
- Packagist symfony/routing: affected >= 2.0.0, < 2.0.19; fixed in 2.0.19
- Packagist symfony/security: affected >= 2.0.0, < 2.0.19; fixed in 2.0.19
- Packagist symfony/http-foundation: affected >= 2.0.0, < 2.0.19; fixed in 2.0.19

## Suggested inspection (read-only)
- Packagist symfony/symfony: check the installed version with your package manager.
- Packagist symfony/routing: check the installed version with your package manager.
- Packagist symfony/security: check the installed version with your package manager.
- Packagist symfony/http-foundation: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on symfony/symfony, symfony/routing, symfony/security, symfony/http-foundation.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-83c3-qx27-2rwr (GitHub-reviewed advisory GHSA-83c3-qx27-2rwr lists affected ranges: Packagist symfony/http-foundation >=2.0.0 =2.0.0 =2.0.0 =2.0.0 <2.0.19)

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