check.c in sudo 1.7.x before 1.7.4p5, when a Runas group is configured, does not require a password for command execution that involves a gid change but no uid change, which allows local users to bypass an intended authentication requirement via the -g option to a sudo command.
bugs.debian.org/cgi-bin/bugreport.cgi?bug=609641
lists.fedoraproject.org/pipermail/package-announce/2011-January/053263.html
lists.fedoraproject.org/pipermail/package-announce/2011-January/053341.html
lists.opensuse.org/opensuse-security-announce/2011-01/msg00006.html
openwall.com/lists/oss-security/2011/01/11/3
openwall.com/lists/oss-security/2011/01/12/1
openwall.com/lists/oss-security/2011/01/12/3
secunia.com/advisories/42886
secunia.com/advisories/42949
secunia.com/advisories/42968
secunia.com/advisories/43068
secunia.com/advisories/43282
security.gentoo.org/glsa/glsa-201203-06.xml
slackware.com/security/viewer.php?l=slackware-security&y=2011&m=slackware-security.593654
www.mandriva.com/security/advisories?name=MDVSA-2011:018
www.osvdb.org/70400
www.redhat.com/support/errata/RHSA-2011-0599.html
www.securityfocus.com/bid/45774
www.sudo.ws/repos/sudo/rev/07d1b0ce530e
www.sudo.ws/repos/sudo/rev/fe8a94f96542
www.sudo.ws/sudo/alerts/runas_group_pw.html
www.ubuntu.com/usn/USN-1046-1
www.vupen.com/english/advisories/2011/0089
www.vupen.com/english/advisories/2011/0182
www.vupen.com/english/advisories/2011/0195
www.vupen.com/english/advisories/2011/0199
www.vupen.com/english/advisories/2011/0212
www.vupen.com/english/advisories/2011/0362
bugzilla.redhat.com/show_bug.cgi?id=668879
exchange.xforce.ibmcloud.com/vulnerabilities/64636