The polkit_backend_action_pool_init function in polkitbackend/polkitbackendactionpool.c in PolicyKit (aka polkit) before 0.113 might allow local users to gain privileges via duplicate action IDs in action descriptions.
https://usn.ubuntu.com/3717-2/
https://security.gentoo.org/glsa/201611-07
https://bugzilla.redhat.com/show_bug.cgi?id=1245673
https://bugs.freedesktop.org/show_bug.cgi?id=83590
http://www.securitytracker.com/id/1035023
http://lists.opensuse.org/opensuse-updates/2015-11/msg00042.html
http://lists.opensuse.org/opensuse-security-announce/2015-10/msg00010.html
http://lists.freedesktop.org/archives/polkit-devel/2015-July/000432.html