Integer overflow in X.org libXtst 1.2.1 and earlier allows X servers to trigger allocation of insufficient memory and a buffer overflow via vectors related to the XRecordGetContext function.
http://www.x.org/wiki/Development/Security/Advisory-2013-05-23
http://www.ubuntu.com/usn/USN-1866-1
http://www.openwall.com/lists/oss-security/2013/05/23/3
http://www.debian.org/security/2013/dsa-2689
http://lists.opensuse.org/opensuse-updates/2013-06/msg00160.html
http://lists.fedoraproject.org/pipermail/package-announce/2013-May/106886.html