---
id: CVE-2026-64284
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits

  Move the handling of fastpath userspace exits into vendor code to ensure
  KVM runs vendor sp…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits

  Move the handling of fastpath userspace exits into vendor code to ensure
  KVM runs vendor sp…
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H'
published: '2026-07-25'
updated: '2026-07-27'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64284'
references:
  - url: 'https://git.kernel.org/stable/c/0ffedf43910e44b76c2c1db4e9fbf12b268190c1'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4ad73ef0e7966ecfe67de0060537b4cb14d9acd4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b3436d9b9b1affe1c3191ac9831308923f5f03c3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f2ca2b5326211bd38490f0497eb583721ce0bbc0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00126
epssPercentile: 0.01952
ingestedAt: '2026-07-27T06:16:50.067Z'
---

## Overview

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

KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits

Move the handling of fastpath userspace exits into vendor code to ensure
KVM runs vendor specific operations that need to run before userspace gains
control of the vCPU.  E.g. for VMX (and soon to be for SVM as well), KVM
needs to flush the PML buffer prior to exiting to userspace, otherwise any
memory written by the final KVM_RUN might never be flagged as dirty.

Note, waiting to snapshot CR0 and CR3 until svm_handle_exit() is flawed in
general, as that risks consuming stale state in a fastpath handler.  That
will be addressed in a future change.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.