http://seclists.org/oss-sec/2015/q2/704

> OpenStack Cinder and Nova do not provide input format to several calls
> of "qemu-img convert".  In Cinder these calls are done as root.  This
> allows the attacker to play the format guessing in qemu-img by providing
> input with a qcow2 signature.  If this signature contains a base file,
> this file will be read by a process running as root and embedded in the
> output.  This bug is similar to CVE-2013-1922 and has been assigned
> CVE-2015-1850.
> 
> Tested with: lvm backed volume storage in Cinder, it may apply to others
> as well.
> 
> Steps to reproduce:
> - create volume and attach to vm,
> - create a qcow2 signature on the volume containing a base-file[1] from
>   within the vm and
> - trigger an upload to Glance with "cinder upload-to-image --disk-type
>   qcow2"[2].
> The image uploaded to Glance will have the base-file from the
> cinder-volume host embedded.
> 
> Affected versions: tested on 2014.1.3, found while reading 2014.2.1
> 
> Timeline:
> - Reported upstream 2015-01-27
> - Published 2015-06-13
> [...]
> 
> [1]: qemu-img create -f qcow2 -b /etc/passwd /dev/vdb
> [2]: The disk-type != raw triggers the use of "qemu-img convert"


References:
https://bugs.launchpad.net/cinder/+bug/1415087
https://bugzilla.redhat.com/show_bug.cgi?id=1231816

Waiting for nova confirmation.