OpenSSH before 3.0.1 with Kerberos V enabled does not properly authenticate users, which could allow remote attackers to login unchallenged.
http://www.securityfocus.com/bid/3560
http://www.openbsd.org/errata30.html#sshd
http://www.iss.net/security_center/static/7598.php
http://msgs.securepoint.com/cgi-bin/get/bugtraq0111/114.html