Network Security Services (NSS) now supports TLS 1.2 with the release of its latest version. NSS 3.15.1 also introduces a number of new types, most of which have to do with the new TLS version. An important encryption mode that NSS does not yet include is encryption with AES Galois Counter Mode (GCM) – this technique is said to prevent attacks such as BEAST and Lucky 13. Users of Firefox Nightly version 25.0a1 can already manually enable the new encryption mode.”]
Source: http://www.h-online.com/security/news/item/NSS-3-15-1-brings-TLS-1-2-support-to-Firefox-1918133.html