The remote host is missing an update to cups, cupsys announced via advisory DSA 1810-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201810-1

Anibal Sacco discovered that cups, a general printing system for UNIX systems, suffers from null pointer dereference because of its handling of two consecutive IPP packets with certain tag attributes that are treated as IPP_TAG_UNSUPPORTED tags. This allows unauthenticated attackers to perform denial of service attacks by crashing the cups daemon. For the oldstable distribution (etch), this problem has been fixed in version 1.2.7-4+etch8 of cupsys. For the stable distribution (lenny), this problem has been fixed in version 1.3.8-1+lenny6 of cups. For the testing distribution (squeeze), this problem will be fixed soon. For the unstable distribution (sid), this problem will be fixed soon. We recommend that you upgrade your cups/cupsys packages.