Mozilla has released a new version of Firefox, which includes patches for 11 security vulnerabilities. Three of the bugs fixed in Firefox 31 are critical, including a use-after-free vulnerability and a handful of memory safety issues.
There are actually several separate use-after-free vulnerabilities patched in Firefox 31, although just one of them is rated critical. That bug lies in the DirectWrite font handling component of the browser.
“Mozilla community member James Kitchener reported a crash in DirectWrite when rendering MathML content with specific fonts due to an error in how font resources and tables are handled. This leads to use-after-free of a DirectWrite font-face object, resulting in a potentially exploitable crash,” the Mozilla advisory says.
“Mozilla developers and community identified identified and fixed several memory safety bugs in the browser engine used in Firefox and other Mozilla-based products. Some of these bugs showed evidence of memory corruption under certain circumstances, and we presume that with enough effort at least some of these could be exploited to run arbitrary code,” Mozilla said.
The full list of vulnerabilities fixed in Firefox 31 includes:
MFSA 2014-66 IFRAME sandbox same-origin access through redirect
MFSA 2014-65 Certificate parsing broken by non-standard character encoding
MFSA 2014-64 Crash in Skia library when scaling high quality images
MFSA 2014-63 Use-after-free while when manipulating certificates in the trusted cache
MFSA 2014-61 Use-after-free with FireOnStateChange event
MFSA 2014-60 Toolbar dialog customization event spoofing
MFSA 2014-59 Use-after-free in DirectWrite font handling
MFSA 2014-58 Use-after-free in Web Audio due to incorrect control message ordering
MFSA 2014-57 Buffer overflow during Web Audio buffering for playback
MFSA 2014-56 Miscellaneous memory safety hazards (rv:31.0 / rv:24.7)
Firefox users should upgrade their browsers as soon as possible to protect themselves against these vulnerabilities.