virt-manager

A new paper and proof-of-concept, "The Invisible Wire: Bidirectional Audio Covert Channels Across VM Boundaries in Default QEMU/KVM Deployments," has been published. The researchers show that with default virt-manager, SPICE, and PipeWire settings, an unprivileged host-side process can both sniff a virtual machine's audio output and inject audio into it, creating a two-way covert channel. The finding matters because it requires no custom configuration and highlights a gap in typical virtualization isolation assumptions.