New Linux Kernel Flaw Gives ARM64 KVM Guests Read-Write Access to Host Memory

CVE-2026-89775 in Linux Kernel ARM64 KVM can let a guest virtual machine retain read-write access to freed host kernel memory when nested virtualization is enabled, potentially enabling a guest-to-host escape. The issue is fixed in Linux 6.18.51, 7.2.5, and 7.3-rc1; no exploitation or public exploit code has been reported, and ARM64 nested virtualization is disabled by default.