source: https://www.securityfocus.com/bid/14617/info

Woltlab Burning Board 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.

It should be noted an attacker must have moderator credentials to access the vulnerable script. 

http://www.example.com/modcp.php?action=post_del&x='SQL_CODE_HERE
http://www.example.com/modcp.php?action=post_del&x=6&y='SQL_CODE_HERE