The remote FTP server is affected by a denial of service vulnerability.
The remote host is running Serv-U File Server, an FTP server for Windows. The installed version of Serv-U 7.x is earlier than 188.8.131.52, and is affected by a denial of service vulnerability. By using a specially crafted command such as XCRC, STOU, DSIZ, AVBL, RNTO, or RMDA, it may be possible for an authenticated attacker to render the FTP server temporarily unresponsive.
Upgrade to version 184.108.40.206 or higher.