Mozilla Firefox before 16.0, Thunderbird before 16.0, and SeaMonkey before 2.13 do not properly handle navigation away from a web page that has a SELECT element's menu active, which allows remote attackers to spoof page content via vectors involving absolute positioning and scrolling.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16184
https://bugzilla.mozilla.org/show_bug.cgi?id=575294
http://www.ubuntu.com/usn/USN-1611-1
http://www.mozilla.org/security/announce/2012/mfsa2012-75.html
http://lists.opensuse.org/opensuse-security-announce/2012-10/msg00010.html