---
id: "CVE-2026-98471"
kind: "vulnerability"
aliases: ["CVE-2026-98471"]
title: "Linux kernel KVM SEV: stale guest data may remain in CPU caches"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["amd-sev", "kvm", "linux", "runtime", "self-hosted", "virtualization"]
not_affected_if: ["no-intra-host-migration", "no-sev-guests"]
published_at: "2026-10-18T16:16:57+00:00"
first_seen_at: "2026-10-23T21:57:15+00:00"
updated_at: "2026-10-25T05:26:02+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98471", "first_seen_at": "2026-10-23T21:57:15+00:00"}]
---

# Linux kernel KVM SEV: stale guest data may remain in CPU caches

During intra-host migration of an SEV guest, the kernel's KVM code did not flush CPU caches for the source VM, so guest memory contents may remain in caches after the VM is destroyed. The sources do not state a concrete attacker outcome beyond leftover stale data.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- `uname -r` to see the running kernel version and compare it against the fixed kernel release in the NVD entry
- unknown whether the sources list affected kernel versions

## Fix

- Update the Linux kernel to a release that includes the upstream KVM SEV fix (the sources do not name the fixed version)
- unknown for the exact patched version

## Timeline

- 2026-10-23T21:57:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98471

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

KVM: SEV: Do cache maintenance on the source VM during intra-host migration

Manually perform cache maintenance on the source VM during intra-host
migration to ensure no stale data is left in CPU caches after the VM is
destroyed.  Because the source VM is "converted" to a non-SEV VM, KVM's
memory reclaim flows won't trigger cache maintenance, e.g. when all guest
memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option
as KVM doesn't require identical guest memory configurations, i.e. the
source VM may have access to memory that the destination VM does not.
Enforcing equivalent memory configurations is infeasible, as it would
require a *deep* comparison of memslots, e.g. to verify that not only are
the memslot identical, but what the memslots point at is also identical.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_