Mozilla Firefox before 7.0 and SeaMonkey before 2.4 do not properly restrict availability of motion data events, which makes it easier for remote attackers to read keystrokes by leveraging JavaScript code running in a background tab.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A13954
https://bugzilla.mozilla.org/show_bug.cgi?id=682562
http://www.usenix.org/events/hotsec11/tech/tech.html#Cai
http://www.mozilla.org/security/announce/2011/mfsa2011-45.html