The Logging Server (Logsrv.exe) in IPSwitch WS_FTP 7.5.29.0 allows remote attackers to cause a denial of service (daemon crash) by sending a crafted packet containing a long string to port 5151/udp.
https://exchange.xforce.ibmcloud.com/vulnerabilities/35396
http://www.vdalabs.com/tools/ipswitch.html
http://secunia.com/advisories/26040
http://packetstormsecurity.org/0707-advisories/wsftp75290-dos.txt