In FreeBSD 13.0-STABLE before n246941-20f96f215562, 12.2-STABLE before r370400, 11.4-STABLE before r370399, 13.0-RELEASE before p4, 12.2-RELEASE before p10, and 11.4-RELEASE before p13, certain VirtIO-based device models in bhyve failed to handle errors when fetching I/O descriptors. A malicious guest may cause the device model to operate on uninitialized I/O vectors leading to memory corruption, crashing of the bhyve process, and possibly arbitrary code execution in the bhyve process.