Summary
The remote host is missing an update to the system as announced in the referenced advisory.
Solution
Update your system with the appropriate patches or software upgrades.
http://www.pizzashack.org/rssh/security.shtml
http://www.vuxml.org/freebsd/a4598875-ec91-11e1-8bd8-0022156e8794.html
Insight
The following package is affected: rssh