CVE-2013-4375 on Ubuntu 12.04 LTS (precise) - medium.
Description:
The qdisk PV disk backend in qemu-xen in Xen 4.2.x and 4.3.x before 4.3.1, and qemu 1.1 and other versions, allows local HVM guests to cause a denial of service (domain grant reference consumption) via unspecified vectors.