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.

Reference:
http://www.mozilla.org/security/announce/2012/mfsa2012-74.html


Acknowledgements:
Red Hat would like to thank the Mozilla project for reporting this issue. Upstream acknowledges Henrik Skupin, Jesse Ruderman and moz_bug_r_a4 as the original reporters. These flaws affect Firefox 15.