The remote host is missing an update to nethack announced via advisory DSA 316-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20316-1

The nethack package is vulnerable to a buffer overflow exploited via a long '-s' command line option. This vulnerability could be used by an attacker to gain gid 'games' on a system where nethack is installed. Additionally, some setgid binaries in the nethack package have incorrect permissions, which could allow a user who gains gid 'games' to replace these binaries, potentially causing other users to execute malicious code when they run nethack. For the stable distribution (woody) these problems have been fixed in version 3.4.0-3.0woody3. For the old stable distribution (potato) problem xxx has been fixed in version 3.3.0-7potato1. For the unstable distribution (sid) these problems are fixed in version 3.4.1-1. We recommend that you update your nethack package.