Mozilla has released Firefox version 12.0 which fixes a number of critical security issues including potential memory corruption. All Firefox users should apply the update as soon as possible.
For more information, see:
Note that Firefox 12 introduces auto-updating features. For areas where auto-updating may break application compatibility, Firefox ESR may be preferred. See http://www.mozilla.org/en-US/firefox/organizations/ for more information. For Firefox ESR admins, the equivalent release is Firefox 10.0.4esr.