The remote host is missing an update to rsync announced via advisory DSA 499-2.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20499-2

A vulnerability was discovered in rsync, a file transfer program, whereby a remote user could cause an rsync daemon to write files outside of the intended directory tree. This vulnerability is not exploitable when the daemon is configured with the 'chroot' option. This update includes an additional fix related to the original vulnerability. For the current stable distribution (woody) this problem has been fixed in version 2.5.5-0.5. For the unstable distribution (sid), this problem has been fixed in version 2.6.1-1. We recommend that you update your rsync package.