The remote host is missing an update to dhcp announced via advisory DSA 584-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20584-1

infamous41md noticed that the log functions in dhcp 2.x, which is still distributed in the stable Debian release, contained pass parameters to function that use format strings. One use seems to be exploitable in connection with a malicious DNS server. For the stable distribution (woody) these problems have been fixed in version 2.0pl5-11woody1. For the unstable distribution (sid) these problems have been fixed in version 2.0pl5-19.1. We recommend that you upgrade your dhcp package.