The remote host is missing an update to clamav announced via advisory DSA 1660-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201660-1

Several denial-of-service vulnerabilities have been discovered in the ClamAV anti-virus toolkit: Insufficient checking for out-of-memory conditions results in null pointer derefences (CVE-2008-3912). Incorrect error handling logic leads to memory leaks (CVE-2008-3913) and file descriptor leaks (CVE-2008-3914). For the stable distribution (etch), these problems have been fixed in version 0.90.1dfsg-4etch15. For the unstable distribution (sid) and the testing distribution (lenny), these problems have been fixed in version 0.94.dfsg-1. We recommend that you upgrade your clamav package.