The remote host is missing an update to prozilla announced via advisory DSA 834-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20834-1

Tavis Ormandy discovered a buffer overflow in prozilla, a multi-threaded download accelerator, which may be exploited to execute arbitrary code. For the old stable distribution (woody) this problem has been fixed in version 1.3.6-3woody3. The stable distribution (sarge) does not contain prozilla packages. The unstable distribution (sid) does not contain prozilla packages. We recommend that you upgrade your prozilla package.