J-Security Center

Title: Fortinet FortiGate URL Filtering Bypass Vulnerability

Severity: MODERATE


Fortinet FortiGate is a series of antivirus firewall devices.

FortiGate is reportedly prone to a URL-filtering bypass. If an HTTP request is submitted with each line terminated by a CR (rather than a CRLF) or if there is no hostname in an HTTP/1.0 request, the device's URL filtering will be bypassed. To comply with RFC 2616, most webservers will parse these malformed HTTP requests, thus returning the requested content to the user.

Note that HTTP requests without the 'Host' header will not likely result in the desired content being returned in name-based virtual hosting webservers.

FortiGate devices running FortiOS v2.8MR10 and v3beta are vulnerable to this issue. Other versions may also be affected.

UPDATE (January 4, 2008): Reports indicate that submitting a fragmented GET or POST request will also bypass the URL filter.

Affected Products:

  • Fortinet FortiOS 2.36.0
  • Fortinet FortiOS 2.5.0
  • Fortinet FortiOS 2.5.00MR4
  • Fortinet FortiOS 2.50.0MR5
  • Fortinet FortiOS 2.8.0 MR10
  • Fortinet FortiOS 2.80.0
  • Fortinet FortiOS 3.0.0 beta


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