The remote host is missing an update to libvirt announced via advisory USN-1094-1.
Details follow:
Petr Matousek discovered that libvirt did not always honor read-only connections. An attacker who is authorized to connect to the libvirt daemon could exploit this to cause a denial of service via application crash.
Solution: The problem can be corrected by upgrading your system to the following package versions:
Ubuntu 9.10: libvirt0 0.7.0-1ubuntu13.3
Ubuntu 10.04 LTS: libvirt0 0.7.5-5ubuntu27.9
Ubuntu 10.10: libvirt0 0.8.3-1ubuntu14.1
In general, a standard system update will make all the necessary changes.