Ubuntu Security Update on VENOM (CVE-2015-3456) [UPDATED]

A buffer overflow in the virtual floppy disk controller of QEMU has been discovered. An attacker could use this issue to cause QEMU to crash or execute arbitrary code in the host’s QEMU process.

This issue is mitigated in a couple ways on Ubuntu when using libvirt to manage QEMU virtual machines, which includes OpenStack’s use of QEMU. The QEMU process in the host environment is owned by a special libvirt-qemu user which helps to limit access to resources in the host environment. Additionally, the QEMU process is confined by an AppArmor profile that significantly lessens the impact of a vulnerability such as VENOM by reducing the host environment’s attack surface.

A fix for this issue has been committed in the upstream QEMU source code tracker. Ubuntu 12.04 LTS, Ubuntu 14.04 LTS, Ubuntu 14.10, and Ubuntu 15.04 are affected. To address the issue, ensure that qemu-kvm 1.0+noroms-0ubuntu14.22 (Ubuntu 12.04 LTS), qemu 2.0.0+dfsg-2ubuntu1.11 (Ubuntu 14.04 LTS), qemu 2.1+dfsg-4ubuntu6.6 (Ubuntu 14.10), qemu 1:2.2+dfsg-5expubuntu9.1 (Ubuntu 15.04) are installed.

For reference, the Ubuntu Security Notices website is the best place to find information on security updates and the affected supported releases of Ubuntu.  Users can get notifications via email and RSS feeds from the USN site, as well as access the Ubuntu CVE Tracker.