Use-after-free vulnerability in the attribute-cloning functionality in the DOM implementation in Mozilla Firefox 3.5.x before 3.5.11 and 3.6.x before 3.6.7, and SeaMonkey before 2.0.6, allows remote attackers to execute arbitrary code via vectors related to deletion of an event attribute node with a nonzero reference count.
https://bugzilla.mozilla.org/show_bug.cgi?id=572986
http://www.zerodayinitiative.com/advisories/ZDI-10-134/
http://www.mozilla.org/security/announce/2010/mfsa2010-35.html