source: http://www.securityfocus.com/bid/45214/info

Alguest 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.

Alguest 1.1c-patched is vulnerable; other versions may also be affected. 

http://www.example.com/alguest/index.php?start=' 