The Mozilla Maintenance Service in Mozilla Firefox before 21.0, Firefox ESR 17.x before 17.0.6, Thunderbird before 17.0.6, and Thunderbird ESR 17.x before 17.0.6 on Windows allows local users to bypass integrity verification and gain privileges via vectors involving junctions.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16915
https://bugzilla.mozilla.org/show_bug.cgi?id=850492
http://www.mozilla.org/security/announce/2013/mfsa2013-44.html