The remote host is missing an update to gnutls13 announced via advisory DSA 1581-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201581-1

Several remote vulnerabilities have been discovered in GNUTLS, an implementation of the SSL/TLS protocol suite. NOTE: The libgnutls13 package, which provides the GNUTLS library, does not contain logic to automatically restart potentially affected services. You must restart affected services manually (mainly Exim, using /etc/init.d/exim4 restart) after applying the update, to make the changes fully effective. Alternatively, you can reboot the system. The following vulnerabilities have been identified: A pre-authentication heap overflow involving oversized session resumption data may lead to arbitrary code execution (CVE-2008-1948). Repeated client hellos may result in a pre-authentication denial of service condition due to a null pointer dereference (CVE-2008-1949). Decoding cipher padding with an invalid record length may cause GNUTLS to read memory beyond the end of the received record, leading to a pre-authentication denial of service condition (CVE-2008-1950). For the stable distribution (etch), these problems have been fixed in version 1.4.4-3+etch1. (Builds for the arm architecture are currently not available and will be released later.) For the unstable distribution (sid), these problems will be fixed soon. We recommend that you upgrade your GNUTLS packages.