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.