sudo 1.6.x before 1.6.9p21, when the runas_default option is used, does not properly set group memberships, which allows local users to gain privileges via a sudo command.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A7216
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10946
https://bugzilla.redhat.com/show_bug.cgi?id=567622
http://www.ubuntu.com/usn/USN-905-1
http://www.sudo.ws/cgi-bin/cvsweb/sudo/set_perms.c.diff?r1=1.30.2.7&r2=1.30.2.8
http://www.securityfocus.com/archive/1/514489/100/0/threaded
http://www.openwall.com/lists/oss-security/2010/02/24/5
http://www.openwall.com/lists/oss-security/2010/02/23/4
http://www.gratisoft.us/bugzilla/show_bug.cgi?id=349
http://www.gentoo.org/security/en/glsa/glsa-201003-01.xml
http://www.debian.org/security/2010/dsa-2006
http://wiki.rpath.com/Advisories:rPSA-2010-0075
http://sudo.ws/repos/sudo/rev/aa0b6c01c462
http://securitytracker.com/id?1023658
http://secunia.com/advisories/38915
http://secunia.com/advisories/38803
http://secunia.com/advisories/38795
http://secunia.com/advisories/38762
http://lists.opensuse.org/opensuse-security-announce/2010-03/msg00004.html