The remote host is vulnerable to a buffer overflow.
The remote host seems to be running a vulnerable version of SlimFTPd, a small FTP server for Windows. It is reported that versions up to 3.15 are prone to a buffer overflow vulnerability that may allow an attacker to execute arbitrary code on this host. A attacker needs a valid FTP account on the server to exploit this vulnerability.
Upgrade to SlimFTPd version 3.16 or higher.