New Zapscape KVM Flaw Could Let Privileged L1 Guest Code Escape to Linux Hosts

Zapscape (CVE-2026-64561) is a KVM/x86 shadow-MMU stale-root use-after-free vulnerability that can allow an L1 guest with kernel (root) privileges to escape nested virtualization isolation and execute code on the host; a public proof-of-concept exists but no confirmed in-the-wild exploitation, and upstream patches have been merged with vendor advisories and fixed stable kernels available.