Interpretation conflict in Fortinet FortiGate 2.8, running FortiOS 2.8MR10 and v3beta, allows remote attackers to bypass the URL blocker via an (1) HTTP request terminated with a line feed (LF) and not carriage return line feed (CRLF) or (2) HTTP request with no Host field, which is still processed by most web servers without violating RFC2616.
https://exchange.xforce.ibmcloud.com/vulnerabilities/24626
http://www.vupen.com/english/advisories/2006/0539
http://www.securityfocus.com/bid/16599
http://www.securityfocus.com/archive/1/424858/100/0/threaded
http://www.fortiguard.com/advisory/FGA-2006-10.html
http://secunia.com/advisories/18844
http://lists.grok.org.uk/pipermail/full-disclosure/2006-February/042140.html