It is supported on Ubuntu 13.10, Ubuntu 12.10, and Ubuntu 12.04 LTS
Canonical has announced on February 10, 2014, that the Mozilla Firefox web browser used in its supported Ubuntu Linux operating systems has been updated to version 27.The Firefox 27 web browser was officially released by Mozilla on February 6, 2014, and it introduces support for TLS 1.1 and TLS 1.2, as well as SPDY 3.1. In addition, Mozilla Firefox 27 brings an improved SocialAPI, several cool features for developers, and various bug fixes.
It took it a few days, but Canonical finally managed to bring the brand new Mozilla Firefox 27 in all its supported Ubuntu platforms, including Ubuntu 13.10 (Saucy Salamander), Ubuntu 12.10 (Quantal Quetzal), and Ubuntu 12.04 LTS (Precise Pangolin).
Therefore, users of the aforementioned Ubuntu OSes are urged to upgrade their systems to the Mozilla Firefox 27 web browser as soon as possible. For that, please use the built-in Update Manager utility.