Mozilla Firefox 43 was recently released and new features and security improvements are enumerated below:

http://www.networkworld.com/article/3015120/internet/first-look-firefox-43.html
https://www.mozilla.org/en-US/firefox/43.0/releasenotes/
https://www.mozilla.org/en-US/security/known-vulnerabilities/firefox/#firefox43

The latest version of Mozilla’s flagship browser is out, and it’s had some small but significant overhauls, chief among which is an update to a 64-bit version, catching up to the other major browsers.  Below are key features:

1. 64 bit addressability support
2. Enhanced Privacy Mode
3. m4v video support
4. On screen keyboard for WIN8 and WIN10 mobile devices
5. Security improvements with 4 critical issues fixed