The Logging Server (ftplogsrv.exe) 7.9.14.0 and earlier in IPSwitch WS_FTP 6.1 allows remote attackers to cause a denial of service (loss of responsiveness) via a large number of large packets to port 5151/udp, which causes the listening socket to terminate and prevents log commands from being recorded, a different vulnerability than CVE-2007-3823.

More... (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2008-0608)