CVE-2026-98718 KVM: SEV: Do cache maintenance on the source VM *before* clearing SEV state
A race condition in KVM SEV migration allows host memory corruption and data leakage due to improper cache flushing order.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98718?
CVE-2026-98718 is a 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: SEV: Do cache maintenance on the source VM *before* clearing SEV state
Explicitly flush caches after intra-host migration before clearing "SEV active" on the source VM, as doing cache maintenance afterwards creates a tiny window where memory reclaim could return memory to the host without performing a cache flush, e.g. as pointed out by Sashiko:
CPU1 in sev_migrate_from(): src->active = false;
CPU2 running concurrent unmap: Since active is false, the automatic cache flush in sev_guest_memory_reclaimed is skipped. The host frees and reallocates the page.
CPU1 in sev_migrate_from(): sev_writeback_caches(src_kvm); Executes a hardware cache flush (wbnoinvd), which writes the guest's old dirty ciphertext over the new page owner's data.
Which versions are affected by CVE-2026-98718?
How do I fix CVE-2026-98718?
Apply the vendor's patch.
Is CVE-2026-98718 being exploited?
There is no known exploitation of CVE-2026-98718 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-98718, DEBIAN-CVE-2026-98718, GHSA-8j5c-4j8r-8m5m, UBUNTU-CVE-2026-98718.