The boot-from-volume feature in OpenStack Compute (Nova) Folsom and Essex, when using nova-volumes, allows remote authenticated users to boot from other users' volumes via a volume id in the block_device_mapping parameter. Per http://www.ubuntu.com/usn/USN-1709-1/
A security issue affects these releases of Ubuntu and its derivatives:
Ubuntu 12.10
Ubuntu 12.04 LTS
Ubuntu 11.10
Publication date: Wed, 13 Feb 2013 22:55:00 +0000