Simple Desktop Display Manager (SDDM) before 0.10.0 allows local users to gain root privileges because code running as root performs write operations within a user home directory, and this user may have created links in advance (exploitation requires the user to win a race condition in the ~/.Xauthority chown case, but not other cases).
https://github.com/sddm/sddm/pull/280
https://bugzilla.redhat.com/show_bug.cgi?id=1149610
http://www.openwall.com/lists/oss-security/2014/10/06/4
http://lists.fedoraproject.org/pipermail/package-announce/2014-October/141550.html
http://lists.fedoraproject.org/pipermail/package-announce/2014-October/141494.html