Symfony 2.7.0 recently released, is a set of PHP Components, a Web Application framework, a Philosophy, and a Community — all working together in harmony. Symfony 2.7.0 comes with more than 100 new features and enhancements. Symfony has now early built-in support for PSR-7. And that works as of Symfony 2.3, without breaking backward compatibility.
Symfony 2.7.0 changelog:
Avoid using the app global variable in the profiler templates
[REVERTED] [TwigBundle] Refresh twig paths when resources change
CVE-2015-4050 [HttpKernel] Do not call the FragmentListener if controller is already defined
[Serializer] AbstractNormalizer::instantiateObject allow default values when not optional