Summary
The remote host is missing an update to fsh
announced via advisory DSA 002-1.
Solution
https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20002-1
Insight
Colin Phipps found an interesting symlink attack problem in fsh (a tool to quickly run remote commands over rsh/ssh/lsh). When fshd starts it creates a directory in /tmp to hold its sockets. It tries to do that securely by checking of it can chown that directory if it already exists to check if it is owner by the user invoking it.
However an attacker can circumvent this check by inserting a symlink to a file that is owner by the user who runs fhsd and replacing that with a directory just before fshd creates the socket.
This has been fixed in version 1.0.post.1-3potato.