An issue was discovered in OpenStack Nova before 23.2.2, 24.x before 24.1.2, and 25.x before 25.0.2. By creating a neutron port with the direct vnictype, creating an instance bound to that port, and then changing the vnictype of the bound port to macvtap, an authenticated user may cause the compute service to fail to restart, resulting in a possible denial of service. Only Nova deployments configured with SR-IOV are affected.