TYPSoft FTP Server 1.10 allows remote attackers to cause a denial of service (CPU consumption) via an empty USER name.
https://exchange.xforce.ibmcloud.com/vulnerabilities/15048
https://euvd.enisa.europa.eu/vulnerability/EUVD-2004-0252
http://www.securitytracker.com/alerts/2004/Feb/1008943.html