virt/disk/api.py in OpenStack Compute (Nova) Folsom (2012.2), Essex (2012.1), and Diablo (2011.3) allows remote authenticated users to overwrite arbitrary files via a symlink attack on a file in an image.
https://review.openstack.org/#/c/9268/
https://lists.launchpad.net/openstack/msg14089.html
https://bugs.launchpad.net/nova/+bug/1015531
http://www.ubuntu.com/usn/USN-1497-1
http://www.securityfocus.com/bid/54278
http://secunia.com/advisories/49802
http://secunia.com/advisories/49763
http://lists.fedoraproject.org/pipermail/package-announce/2012-July/083984.html
http://lists.fedoraproject.org/pipermail/package-announce/2012-July/083969.html