WFTPD Pro Server 3.21 Release 1 allows a remote attacker to allocate arbitrary amounts of memory and force the WFTPD server process to use 100% of the CPU. Another DoS vulnerability allows an attacker to send a special string to crash WFTPD.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/32788/wftpdDoS.txt
Source: https://packetstormsecurity.com/files/32788/wftpdDoS.txt.html