CVE-2026-46317
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk3th percentile - higher than 3% of all known CVEs
Summary
In the Linux kernel's KVM for ARM64, a vulnerability was found where the nested_mmus array is reassigned without proper locking. The array is walked under mmu_lock, but reallocation and freeing of the old buffer only used config_lock, leading to a potential use-after-free.
Risk Assessment
An attacker could exploit this to access freed kernel memory, potentially causing system crashes, information leaks, or privilege escalation.
Recommendation
Immediately update the Linux kernel to a version containing the fix that ensures proper synchronization during nested_mmus array reassignment under mmu_lock.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Reassign nested_mmus array behind mmu_lock kvm->arch.nested_mmus[] is walked under kvm->mmu_lock, including from the MMU notifier path (kvm_unmap_gfn_range() -> kvm_nested_s2_unmap()), which can run at any time. kvm_vcpu_init_nested() reallocates the array and frees the old buffer while holding only kvm->arch.config_lock, so such a walker can reference the freed array. Allocate the new array outside of mmu_lock, as the allocation can sleep. Under the lock, copy the existing entries, fix up the back pointers and reassign the array. Free the old buffer after dropping the lock, as kvfree() can sleep as well.