The MITRE CVE dictionary describes this issue as:
OpenStack Compute (Nova) Folsom, Grizzly, and Havana does not properly verify the virtual size of a QCOW2 image, which allows local users to cause a denial of service (host file system disk consumption) via a compressed QCOW2 image. NOTE: this issue is due to an incomplete fix for CVE-2013-2096.
Find out more about CVE-2013-4463 from the
MITRE CVE dictionary dictionary and
The Red Hat Security Response Team has rated this issue as having moderate security impact. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.