OpenStack Compute (Nova) Grizzly, Folsom (2012.2), and Essex (2012.1) allows remote authenticated users to gain access to a VM in opportunistic circumstances by using the VNC token for a deleted VM that was bound to the same VNC port.
"https://github.com/pypa/advisory-database/blob/main/vulns/nova/PYSEC-2013-43.yaml"