source: https://www.securityfocus.com/bid/48914/info

Trading Marketplace script is prone to an SQL-injection vulnerability because the application fails to properly sanitize user-supplied input before using it in an SQL query.

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/selloffers.php?cid=[SQL]