The Mozilla product family has received some key updates as documented below:

https://www.mozilla.org/security/known-vulnerabilities/firefox.html

https://www.mozilla.org/en-US/firefox/20.0/releasenotes/
http://www.mozilla.org/security/known-vulnerabilities/thunderbird.html#thunderbird17.0.5

https://www.mozilla.org/en-US/thunderbird/17.0.5/releasenotes