Mozilla developers 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.
In general these flaws cannot be exploited through email in the Thunderbird and SeaMonkey products because scripting is disabled, but are potentially a risk in browser or browser-like contexts in those products.
Gary Kwong, Jesse Ruderman, Christian Holler, Bob Clary, Kyle Huey, Ed Morley, Chris Lord, Boris Zbarsky, Julian Seward, and Bill McCloskey reported memory safety problems and crashes that affect Firefox 16.
Jesse Ruderman, Andrew McCreight, Bob Clary, and Kyle Huey reported memory safety problems and crashes that affect Firefox ESR 10 and Firefox 16.