source: https://www.securityfocus.com/bid/58911/info

PHP Address Book is prone to multiple SQL-injection vulnerabilities because it fails to sufficiently sanitize user-supplied input.

A successful exploit may allow an attacker to compromise the application, access or modify data, or exploit latent vulnerabilities in the underlying database.

PHP Address Book 8.2.5 is vulnerable; other versions may also be affected.

http://www.example.com/addressbook/register/delete_user.php?id={insert}