eXtropia Web Store remote file retrieval

Summary
eXtropia's Web Store shopping cart program allows the remote file retrieval of any file that ends in a .html extension. Further, by supplying a URL with an imbedded null byte, the script can be made to retrieve any file at all. Example: GET /cgi-bin/Web_Store/web_store.cgi?page=../../../../etc/passwd%00.html will return /etc/passwd.
Solution
None available at this time