Mozilla developers and community 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.
Christian Holler, David Major, Jesse Ruderman, Tyson Smith, Boris Zbarsky, Randell Jesup, Olli Pettay, Karl Tomlinson, Jeff Walden, Gary Kwong, and Andrew McCreight reported memory safety problems and crashes that affect Firefox ESR 38.3 and Firefox 41.
Christian Holler, Andrew McCreight, Georg Fritzsche, Tyson Smith, and Carsten Book reported crash and memory safety problems that affect Firefox 41.