Mozilla developers identified and fixed several stability bugs in the browser engine used in Firefox and other Mozilla-based products. Some of these crashes 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.
Bob Clary reported a crash in the browser engine which affected Firefox 3.6 only.
Jesse Ruderman reported a crash in the browser engine which affected Firefox 3.6 for Mac only.
Bob Clary and Carsten Book reported crashes in the browser engine which affected all supported versions of the browser engine.