The remote host is missing an update to prozilla announced via advisory DSA 663-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20663-1

Several buffer overflows have been discovered in prozilla, a multi-threaded download accelerator which could be exploited by a remote attacker to execute arbitrary code on the victim's machine. An exploit for prozilla is already in the wild. For the stable distribution (woody) these problems have been fixed in version 1.3.6-3woody1. For the unstable distribution (sid) these problems have been fixed in version 1.3.7.3-1 We recommend that you upgrade your prozilla package.