source: https://www.securityfocus.com/bid/15700/info
phpYellowTM is prone to multiple SQL injection vulnerabilities. These issues are 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/print_me.php?ckey=[SQL]