The remote host is missing an update to rsync announced via advisory DSA 404-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20404-1

The rsync team has received evidence that a vulnerability in all versions of rsync prior to 2.5.7, a fast remote file copy program, was recently used in combination with a Linux kernel vulnerability to compromise the security of a public rsync server. While this heap overflow vulnerability could not be used by itself to obtain root access on an rsync server, it could be used in combination with the recently announced do_brk() vulnerability in the Linux kernel to produce a full remote compromise. Please note that this vulnerability only affects the use of rsync as an rsync server. To see if you are running a rsync server you should use the command netstat -a -n to see if you are listening on TCP port 873. If you are not listening on TCP port 873 then you are not running an rsync server. For the stable distribution (woody) this problem has been fixed in version 2.5.5-0.2. For the unstable distribution (sid) this problem has been fixed in version 2.5.6-1.1. However, since the Debian infrastructure is not yet fully functional after the recent break-in, packages for the unstable distribution are not able to enter the archive for a while. Hence they were placed in my home directory on the security machine: <http://klecker.debian.org/~joey/rsync/> We recommend that you upgrade your rsync package immediately if you