The VMScape vulnerability is a Spectre variant that "allows a malicious KVM guest to leak sensitive information such as encryption/decryption keys from a userspace hypervisor such as QEMU". Greg Kroah-Hartman has announced the 6.16.7, 6.12.47, 6.6.106, 6.1.152, 5.15.193, and 5.10.244 stable kernels, which add a mitigation for the hardware bug.