Narcissus could allow a remote attacker to execute arbitrary commands on the system, caused by the improper validation of input by the backend.php script. By sending a specially-crafted POST request, an attacker could exploit this vulnerability to execute arbitrary commands on the system.
Exploit
The following exploit input is available:
http://downloads.securityfocus.com/vulnerabilities/exploits/56511.php.txt
http://downloads.securityfocus.com/vulnerabilities/exploits/56511.rb