Description of problem: /var/lib/nova/instances/ can contain a sensitive data, it should not be world readable/list-able. Version-Release number of selected component (if applicable): 13.0.0.0b4-0.20160307070815.38c3f88.fc23.
This bug is against a Version which has reached End of Life. If it's still present in supported release (http://releases.openstack.org), please update Version and reopen.