The new vuln glories in the name XSA-138, aka CVE-2015-5154 and means “An HVM guest which has access to an emulated IDE CDROM device (e.g. with a device with "devtype=cdrom", or the "cdrom" convenience alias, in the VBD configuration) can exploit this vulnerability to take over the qemu process elevating its privilege to that of the qemu process.”