Mozilla Firefox before 3.5.19 and 3.6.x before 3.6.17, and SeaMonkey before 2.0.14, does not properly use nsTreeRange data structures, which allows remote attackers to execute arbitrary code via unspecified vectors that lead to a "dangling pointer."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A14020
https://bugzilla.mozilla.org/show_bug.cgi?id=630919
http://www.mozilla.org/security/announce/2011/mfsa2011-13.html
http://www.mandriva.com/security/advisories?name=MDVSA-2011:079
http://www.debian.org/security/2011/dsa-2235
http://www.debian.org/security/2011/dsa-2228
http://www.debian.org/security/2011/dsa-2227
http://securityreason.com/securityalert/8310