Mozilla Firefox 3.6.x before 3.6.7 and Thunderbird 3.1.x before 3.1.1 do not properly implement access to a content object through a SafeJSObjectWrapper (aka SJOW) wrapper, which allows remote attackers to execute arbitrary JavaScript code with chrome privileges by leveraging "access to an object from the chrome scope."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11527
https://bugzilla.mozilla.org/show_bug.cgi?id=567069
http://www.mozilla.org/security/announce/2010/mfsa2010-38.html