Buffer overflow in X.org libXxf86vm 1.1.2 and earlier allows X servers to cause a denial of service (crash) and possibly execute arbitrary code via crafted length or index values to the XF86VidModeGetGammaRamp function.
http://www.x.org/wiki/Development/Security/Advisory-2013-05-23
http://www.ubuntu.com/usn/USN-1870-1
http://www.openwall.com/lists/oss-security/2013/05/23/3
http://www.debian.org/security/2013/dsa-2692
http://lists.opensuse.org/opensuse-updates/2013-06/msg00165.html
http://lists.fedoraproject.org/pipermail/package-announce/2013-May/106872.html