source: https://www.securityfocus.com/bid/16520/info

UBB.Threads is prone to an SQL-injection vulnerability. This issue is due to a failure in the application to properly sanitize user-supplied input before using it in an SQL query.

Successful exploitation could allow an attacker to compromise the application, access or modify data, or exploit vulnerabilities in the underlying database implementation.

This issue is reported to affect UBB.Threads version 6.3; other versions may also be vulnerable. 

http://www.example.com/showflat.php?Cat=&Number=19229%20UNION%20SELECT%201,2%20/*&page=0&view=collapsed&sb=5&o=&fpart=1