The most critical issues are bugs in the browser’s JavaScript and layout engines that could be exploited by attackers to run unauthorized software on a victim’s PC, Mozilla said. The flaws also affect Mozilla’s Thunderbird e-mail client and SeaMonkey Internet software suite.
The update, Firefox’s first of the year, also fixes five other security bugs in the browser, all of which are considered less critical.
The update includes some other performance and stability improvements, including new code that will help scripted commands, such as those used by Adblock Plus, to work better with plug-ins, and addresses a few display issues reported by users.