Gnat-TGP 'DOCUMENT_ROOT' Parameter Remote File Include Vulnerability

Summary
This host is running Gnat-TGP and is prone remote file include vulnerability
Impact
Successful exploitation will let attackers to execute arbitrary code in a user's browser session in the context of an affected site. Impact Level: Application
Solution
No solution or patch was made available for at least one year since disclosure of this vulnerability. Likely none will be provided anymore. General solution options are to upgrade to a newer release, disable respective features, remove the product or replace the product by another one.
Insight
The flaw is due to the error in the 'DOCUMENT_ROOT' parameter, which allows remote attackers to send a specially-crafted URL request to the 'tgpinc.php' script.
Affected
Gnat-TGP version 1.2.20 and prior
References