The Virtio Vring implementation in QEMU allows local OS guest users to cause a denial of service (divide-by-zero error and QEMU process crash) by unsetting vring alignment while updating Virtio rings.
https://www.debian.org/security/2018/dsa-4213
https://usn.ubuntu.com/3575-1/
https://lists.gnu.org/archive/html/qemu-devel/2017-12/msg00166.html