CVE-2026-98440 KVM: arm64: nv: Delay freeing of shadow S2 structures until VM destruction
A use-after-free vulnerability in the Linux kernel's KVM arm64 nested virtualization allows local attackers to potentially execute code or escalate privileges.
- 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-2026-98440?
CVE-2026-98440 is a high-severity use after free vulnerability in Linux, published on 18 Oct 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: nv: Delay freeing of shadow S2 structures until VM destruction
We free the shadow S2 structures from kvm_arch_flush_shadow_all(), which is a Bad Idea(tm). Freeing the page tables is fair game (this is what this callback is for), but freeing the container that could still be referenced by another part of the system is not great.
Instead, grow separate destructors that gets called when we tear the VM down for good. From there, we can nuke both the individual MMUs as well as the global array that points to them, safe in the knowledge that the vcpus themselves have been destroyed already.
Which versions are affected by CVE-2026-98440?
How do I fix CVE-2026-98440?
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-2026-98440 being exploited?
There is no known exploitation of CVE-2026-98440 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98440, DEBIAN-CVE-2026-98440, GHSA-f55r-7vvq-j4jq, UBUNTU-CVE-2026-98440.