The SSH1 PAM challenge response authentication in OpenSSH 3.7.1 and 3.7.1p1, when Privilege Separation is disabled, does not check the result of the authentication attempt, which can allow remote attackers to gain privileges.
http://www.securityfocus.com/bid/8677
http://www.securityfocus.com/archive/1/338617
http://www.securityfocus.com/archive/1/338616
http://www.openssh.com/txt/sshpam.adv
http://www.kb.cert.org/vuls/id/602204
http://lists.grok.org.uk/pipermail/full-disclosure/2003-September/010812.html