Linux KVM ARM64 Nested Virtualization Memory Translation Flaw

CVE-2026-80665 is a high-severity vulnerability in the Linux kernel's KVM hypervisor affecting ARM64 nested virtualization (nv) functionality. The flaw exists in the kvm_translate_vncr() function, which fails to properly handle late-stage failures during Stage 1 (S1) memory translation when resolving guest physical addresses to host physical frame numbers (PFN). Specifically, when a guest frame number (GFN) falls outside valid memory slots, the function returns -EFAULT without properly signaling an external abort (SEA) to the guest, causing inconsistent guest state and potential denial of service. This affects system administrators and cloud providers running nested KVM environments on ARM64 platforms, particularly those supporting live VM migration or complex nested VM topologies.

While Casky.ai currently has zero mapped skills for this specific CVE, a complete security detection framework would correlate this vulnerability with MITRE ATT&CK techniques under Resource Development and Impact categories. Practitioners using extended AI reasoning would identify attack patterns including: (1) Privilege Escalation attempts through hypervisor escape via malformed memory translation requests, (2) Denial of Service through crafted nested VM configurations that trigger unhandled translation failures, and (3) Defense Evasion by exploiting inconsistent abort handling to hide malicious nested VM activity. Detection would focus on monitoring nested virtualization syscalls, unexpected EFAULT returns without corresponding SEA signals, and anomalous GFN access patterns from nested guests—patterns that Claude's reasoning capabilities could correlate across system logs and hypervisor traces to identify exploitation attempts.