Mozilla has released a substantial security update to the popular Web browser Firefox [1]. While release notes are terse, saying only that the update fixes "several stability/security issues", the bug list [2] indicates several critical vulnerabilities have been addressed, including three that could be exploited to crash the browser and run arbitrary code. (Free, 17.6 MB)
[1]: http://www.mozilla.com/en-US/firefox/personal.html
[2]: http://www.mozilla.org/security/known-vulnerabilities/firefox35.html#firefox3.5.6