When investigating issue #11093, Jeremy Derussé found a serious code injection issue in the way Symfony implements translation caching in FrameworkBundle.

• Your Symfony application is vulnerable if you meet the following conditions:

• You are using the Symfony translation system from FrameworkBundle (so basically if you are using Symfony full-stack -- you are not affected if you are using the Translation component with Silex for instance);
  You don't sanitize locales coming from a URL (any route with a _locale argument for instance):

When vulnerable, an attacker can submit a non-valid locale value that can contain some PHP code that will be executed by Symfony. That's because the locale value is dumped into a PHP file generated in the cache without being sanitized first.

References

• https://github.com/symfony/symfony/commit/06a80fbdbe744ad6f3010479ba64ef5cf35dd9af.patch
• https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/framework-bundle/CVE-2014-4931.yaml
• https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2014-4931.yaml
• https://symfony.com/blog/security-releases-cve-2014-4931-symfony-2-3-18-2-4-8-and-2-5-2-released