CVE-2026-46317 KVM: arm64: Reassign nested_mmus array behind mmu_lock
A use-after-free in the Linux kernel's KVM arm64 module allows attackers to potentially execute code or escalate privileges via race conditions in nested MMU handling.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-46317?
CVE-2026-46317 is a high-severity use after free vulnerability in Linux kernel, published on 9 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-416
Which versions are affected by CVE-2026-46317?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-46317?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-46317 being exploited?
There is no known exploitation of CVE-2026-46317 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-46317, DEBIAN-CVE-2026-46317, GHSA-5vrh-8j67-jvj4, ROOT-OS-DEBIAN-13-CVE-2026-46317, UBUNTU-CVE-2026-46317.