Finjan Software SurfinGate 6.0 and 6.0 1 allows remote attackers to bypass URL access restrictions via a URL with an IP address instead of a hostname.
http://www.securityfocus.com/bid/5629
http://www.iss.net/security_center/static/10038.php
http://archives.neohapsis.com/archives/bugtraq/2002-09/0043.html
http://archives.neohapsis.com/archives/bugtraq/2002-09/0032.html