Cisco ONS15454 and ONS15327 running ONS before 3.4 allows remote attackers to modify the system configuration and delete files by establishing an FTP connection to the TCC, TCC+ or XTC using a username and password that does not exist.
http://www.securityfocus.com/bid/6076
http://www.iss.net/security_center/static/10505.php
http://www.cisco.com/warp/public/707/ons-multiple-vuln-pub.shtml