source: https://www.securityfocus.com/bid/13608/info

DirectTopics 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 result in a compromise of the application, disclosure or modification of data, or may permit an attacker to exploit vulnerabilities in the underlying database implementation.

http://www.example.com/topic.php?topic=669%B4SQL%20INJECTION