The fbComposite function in fbpict.c in the Render extension in the X server in X.Org X11R7.1 allows remote authenticated users to cause a denial of service (memory corruption and daemon crash) or possibly execute arbitrary code via a crafted request, related to an incorrect macro definition.
https://rhn.redhat.com/errata/RHSA-2010-0382.html
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10112
https://bugzilla.redhat.com/show_bug.cgi?id=582601
https://bugzilla.redhat.com/show_bug.cgi?id=495733
http://www.vupen.com/english/advisories/2010/1185
http://www.ubuntu.com/usn/USN-939-1
http://securitytracker.com/id?1023929
http://secunia.com/advisories/39834
http://secunia.com/advisories/39650
http://lists.opensuse.org/opensuse-security-announce/2010-08/msg00001.html