Multiple integer overflows in X.org libXext 1.3.1 and earlier allow X servers to trigger allocation of insufficient memory and a buffer overflow via vectors related to the (1) XcupGetReservedColormapEntries, (2) XcupStoreColors, (3) XdbeGetVisualInfo, (4) XeviGetVisualInfo, (5) XShapeGetRectangles, and (6) XSyncListSystemCounters functions.
http://www.x.org/wiki/Development/Security/Advisory-2013-05-23
http://www.ubuntu.com/usn/USN-1857-1
http://www.openwall.com/lists/oss-security/2013/05/23/3
http://www.debian.org/security/2013/dsa-2682
http://lists.opensuse.org/opensuse-updates/2013-06/msg00139.html