The remote host is missing an update to nvi, nvi-m17n announced via advisory DSA 085-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20085-1

Takeshi Uno found a very stupid format string vulnerability in all versions of nvi (in both, the plain and the multilingualized version). When a filename is saved, it ought to get displayed on the screen. The routine handling this didn't escape format strings. This problem has been fixed in version 1.79-16a.1 for nvi and 1.79+19991117-2.3 for nvi-m17n for the stable Debian GNU/Linux 2.2. Even if we don't believe that this could lead into somebody gaining access of another users account if he hasn't lost his brain, we recommend that you upgrade your nvi packages.