sudo 1.6.x and 1.7.x before 1.7.9p1, and 1.8.x before 1.8.4p5, does not properly support configurations that use a netmask syntax, which allows local users to bypass intended command restrictions in opportunistic circumstances by executing a command on a host that has an IPv4 address.
https://www.suse.com/security/cve/CVE-2012-2337/
https://bugzilla.redhat.com/show_bug.cgi?id=820677
http://www.sudo.ws/sudo/alerts/netmask.html
http://www.securitytracker.com/id?1027077
http://www.mandriva.com/security/advisories?name=MDVSA-2012:079
http://www.debian.org/security/2012/dsa-2478
http://secunia.com/advisories/49948
http://secunia.com/advisories/49291
http://secunia.com/advisories/49244
http://secunia.com/advisories/49219
http://lists.fedoraproject.org/pipermail/package-announce/2012-May/081432.html