updater.exe in Mozilla Firefox before 41.0 and Firefox ESR 38.x before 38.3 on Windows allows local users to write to arbitrary files by conducting a junction attack and waiting for an update operation by the Mozilla Maintenance Service.
https://bugzilla.mozilla.org/show_bug.cgi?id=1177861
http://www.securitytracker.com/id/1033640
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
http://www.mozilla.org/security/announce/2015/mfsa2015-100.html
http://lists.opensuse.org/opensuse-security-announce/2015-10/msg00005.html
http://lists.opensuse.org/opensuse-security-announce/2015-10/msg00003.html
http://lists.opensuse.org/opensuse-security-announce/2015-10/msg00000.html