CVE-2026-98164 KVM: x86/mmu: Check write tracking in all address spaces
A logic error in KVM's write tracking allows triggering a kernel BUG, causing a denial of service.
- 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-2026-98164?
CVE-2026-98164 is a high-severity memory corruption vulnerability in Linux kernel, published on 29 Sep 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: x86/mmu: Check write tracking in all address spaces
kvm_gfn_is_write_tracked() checks only the supplied memslot, but page tracking is per-address-space and shadow pages are shared across all address spaces. With SMM, a GFN can therefore be write-tracked in one address space and appear untracked through the other.
Check the supplied slot first, then the slot for the other address space. This ensures all callers honor write tracking regardless of the active address space. In particular, it prevents mmu_try_to_unsync_pages() from marking an upper-level shadow page unsync and eventually triggering the BUG in pte_list_remove().
[invert direction of the conditional. - Paolo]
Weakness: CWE-670
Which versions are affected by CVE-2026-98164?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-98164?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-98164 being exploited?
There is no known exploitation of CVE-2026-98164 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-98164, DEBIAN-CVE-2026-98164, GHSA-4wvx-xqjp-p7g6, UBUNTU-CVE-2026-98164.