Integer overflow in X.org libXinerama 1.1.2 and earlier allows X servers to trigger allocation of insufficient memory and a buffer overflow via vectors related to the XineramaQueryScreens function.
http://lists.fedoraproject.org/pipermail/package-announce/2013-May/106845.html
http://lists.opensuse.org/opensuse-updates/2013-06/msg00154.html
http://www.debian.org/security/2013/dsa-2691