Mozilla Updater in Mozilla Firefox before 24.0, Firefox ESR 17.x before 17.0.9, Thunderbird before 24.0, Thunderbird ESR 17.x before 17.0.9, and SeaMonkey before 2.21 does not ensure exclusive access to a MAR file, which allows local users to gain privileges by creating a Trojan horse file after MAR signature verification but before MAR use.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A18821
https://bugzilla.mozilla.org/show_bug.cgi?id=890853
http://www.mozilla.org/security/announce/2013/mfsa2013-83.html
http://lists.fedoraproject.org/pipermail/package-announce/2013-September/117526.html
http://lists.fedoraproject.org/pipermail/package-announce/2013-September/116610.html
http://lists.fedoraproject.org/pipermail/package-announce/2013-September/115907.html