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.extmail.org/forum/thread-7260-1-1.html
http://www.vuxml.org/freebsd/44c8694a-12f9-11dd-9b26-001c2514716c.html
Insight
The following package is affected: extman