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 product because scripting is disabled, but are potentially a risk in browser or browser-like contexts.
Gary Kwong, Jesse Ruderman, and Andrew McCreight reported memory safety problems and crashes that affect Firefox ESR 17, and Firefox 21.


External Reference:

http://www.mozilla.org/security/announce/2013/mfsa2013-49.html


Acknowledgements:

Red Hat would like to thank the Mozilla project for reporting this issue. Upstream acknowledges Gary Kwong, Jesse Ruderman, and Andrew McCreight as the original reporter.