Race condition in the pkexec utility and polkitd daemon in PolicyKit (aka polkit) 0.96 allows local users to gain privileges by executing a setuid program from pkexec, related to the use of the effective user ID instead of the real user ID.
https://bugzilla.redhat.com/show_bug.cgi?id=692922
http://www.ubuntu.com/usn/USN-1117-1
http://www.redhat.com/support/errata/RHSA-2011-0455.html
http://www.mandriva.com/security/advisories?name=MDVSA-2011:086
http://www.debian.org/security/2011/dsa-2319
http://securityreason.com/securityalert/8424
http://security.gentoo.org/glsa/glsa-201204-06.xml
http://secunia.com/advisories/48817
http://lists.fedoraproject.org/pipermail/package-announce/2011-May/059859.html
http://lists.fedoraproject.org/pipermail/package-announce/2011-April/058752.html