Linux KVM/arm64 Vulnerability Lets Attackers Escape Virtual Machines and Gain Host Access
Brief
A newly disclosed Linux kernel vulnerability, tracked as CVE-2026-89775, could let attackers escape an ARM64 virtual machine and access the underlying host system.
The issue affects KVM/arm64 environments where nested virtualization is enabled, creating a serious risk for multi-tenant cloud infrastructure and systems that allow untrusted users to create virtual machines.
Security researcher Hyunwoo Kim reported that the flaw stems from a type truncation issue in the KVM/arm64 stage-1 page-table walk process.
The bug affects how the kernel calculates the size of a memory region it must invalidate from the virtual CPU’s pseudo Translation Lookaside Buffer, or pseudo-TLB.
Under normal conditions, KVM must invalidate stale memory translations after memory mappings change.