Fortinet advises that a recently discovered URL Filtering application bypass vulnerability was found and published on some public websites. The Fortinet Engineering team has reviewed it and provided a fix for it.
(CVE Reference: CAN-2005-3057)

Original public website description:
"Fortinet's URL blocking functionality can be bypassed by specially-crafted HTTP requests that are terminated by the CR character instead of the CRLF characters. It is also possible to bypass the functionality via a HTTP/1.0 request with no host header."

Fortinet's Analysis:
The author's original description is actually inaccurate. A more accurate description is:
"....HTTP requests that are terminated by LR character instead of CRLF characters..." as analysis of the author's PERL script showed.

Moreover, while it is possible "to bypass the functionality via an HTTP/1.0 request with no host header", the use of a host field is actually required to access a specific site on multi-homed web sites. When no host header is used, the intended web site is actually not displayed. Therefore, there is no risk.

Products affected:
All FortiGate models running FortiGuard Web Filtering services.


A fix for the single LR character issue has been provided in FortiOS 3.0 GA release and in FortiOS 2.80 MR 12. A special build can be made available to customers who need an immediate fix.