GNOME Display Manager (gdm) before 2.32.2, when glib 2.28 is used, enables execution of a web browser with the uid of the gdm account, which allows local users to gain privileges via vectors involving the x-scheme-handler/http MIME type.
https://hermes.opensuse.org/messages/8643655
https://bugzilla.redhat.com/show_bug.cgi?id=709139
http://www.ubuntu.com/usn/USN-1142-1
http://www.securityfocus.com/bid/48084
http://secunia.com/advisories/44808
http://secunia.com/advisories/44797
http://lists.fedoraproject.org/pipermail/package-announce/2011-June/061264.html
http://git.gnome.org/browse/gdm/commit/?id=d13dd72531599ab7e4c747db3b58a8c17753e08d
http://ftp.gnome.org/pub/GNOME/sources/gdm/2.32/gdm-2.32.2.news