A vulnerability was discovered in oVirt 4.1.x before 4.1.9, where the combination of Enable Discard and Wipe After Delete flags for VM disks managed by oVirt, could cause a disk to be incompletely zeroed when removed from a VM. If the same storage blocks happen to be later allocated to a new disk attached to another VM, potentially sensitive data could be revealed to privileged users of that VM.
https://gerrit.ovirt.org/#/c/84875/
https://gerrit.ovirt.org/#/c/84861/
https://bugzilla.redhat.com/show_bug.cgi?id=1549944