source: https://www.securityfocus.com/bid/15837/info

PhpWebGallery is prone to multiple SQL-injection vulnerabilities because the application fails to properly sanitize user-supplied input before using it in SQL queries.

A successful exploit could allow an attacker to compromise the application, access or modify data, or exploit vulnerabilities in the underlying database. 

http://www.example.com/comments.php?keyword=&author=&cat=0&since=[SQL]
http://www.example.com/comments.php?keyword=&author=&cat=0&since=1&sort_by=[SQL]
http://www.example.com/comments.php?keyword=&author=&cat=0&since=1&sort_by=date&sort_order=descending&items_number=[SQL]