HyperKit is a toolkit for embedding hypervisor capabilities in an application. In versions 0.20210107 and prior of HyperKit, `virtio.c` has is a call to `vc_cfgread` that does not check for null which when called makes the host crash. This issue may lead to a guest crashing the host causing a denial of service. This issue is fixed in commit df0e46c7dbfd81a957d85e449ba41b52f6f7beb4.