TransSoft's Broker FTP Server 3.x and 4.x is vulnerable to a buffer overflow that can allow a malicious attacker to consume all available memory and computing resources.
By sending a username of approximately 6000 characters Broker FTP Server will consume all available Windows NT resources. For example;
C:\>Telnet vulnerabletestsite.com 21
The vendor, TransSoft has released a fix for this vulnerability available at; http://www.transsoft.com/broker/updates/broker40nt.exe