CVE-2026-98718

/// Technical 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.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References