The virFileNBDDeviceAssociate function in util/virfile.c in libvirt 1.1.2 and earlier allows remote authenticated users to cause a denial of service (uninitialized pointer dereference and crash) via unspecified vectors.
http://libvirt.org/git/?p=libvirt.git;a=commitdiff;h=2dba0323ff0cec31bdcea9dd3b2428af297401f2
http://secunia.com/advisories/60895