The remote host is missing an update to libvirt announced via advisory DSA 2194-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202194-1

It was discovered that libvirt, a library for interfacing with different virtualization systems, did not properly check for read-only connections. This allowed a local attacker to perform a denial of service (crash) or possibly escalate privileges. The oldstable distribution (lenny) is not affected by this problem. For the stable distribution (squeeze), this problem has been fixed in version 0.8.3-5+squeeze1. For the testing distribution (wheezy), this problem will be fixed soon. For the unstable distribution (sid), this problem has been fixed in version 0.8.8-3. We recommend that you upgrade your libvirt packages.