source: https://www.securityfocus.com/bid/16642/info

PHP Classifieds 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 allow an attacker to compromise the application, access or modify data, or exploit vulnerabilities in the underlying database implementation. An attacker can exploit this issue to bypass the authentication mechanism and gain access as an arbitrary user.

The following proof of concept is available:
email@example.com' -- '