The remote host is missing an update to proftpd-dfsg announced via advisory DSA 1689-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201689-1

Maksymilian Arciemowicz of securityreason.com reported that ProFTPD is vulnerable to cross-site request forgery (CSRF) attacks and executes arbitrary FTP commands via a long ftp:// URI that leverages an existing session from the FTP client implementation in a web browser. For the stable distribution (etch) this problem has been fixed in version 1.3.0-19etch2 and in version 1.3.1-15~bpo40+1 for backports. For the testing (lenny) and unstable (sid) distributions this problem has been fixed in version 1.3.1-15. We recommend that you upgrade your proftpd-dfsg package.