---
id: CVE-2026-64604
title: 'KVM: VMX: Grab vmcs12 on CR8 interception update iff vCPU is in guest mode'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  KVM: VMX: Grab vmcs12 on CR8 interception update iff vCPU is in guest mode

  When updating CR8 intercepts, get vmcs12 if and only if the vCPU is in
  guest mode so that a …
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 <
    c7cd3605244c924249dea32632e1bc3e89bda543
  - >-
    Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 <
    9a21f1defd96c6301c5fb462a78eb51b191bd2dd
  - >-
    Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 <
    570af5db081b87374594a00711ac5760d2ea6844
  - >-
    Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 <
    ffaaff82336db84e9b58e7a3e81c2fd64e05ed7a
  - >-
    Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 <
    258ec63c0f281bf7b50f9de67c8e93b5b7be5ed4
  - >-
    Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 <
    3dcfb04dd43b16fa1240fc6487fff578ad57264c
  - >-
    Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 <
    db8407b9fd06d857a4a5e8bcff1d086d13007711
  - >-
    Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 <
    7ef78d71ca713d8c00f7c34ddcf276c808143f77
  - Linux 3.18
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T16:42:06.934606Z'
published: '2026-08-06'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T16:44:58.242Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-64604'
references:
  - url: 'https://git.kernel.org/stable/c/c7cd3605244c924249dea32632e1bc3e89bda543'
  - url: 'https://git.kernel.org/stable/c/9a21f1defd96c6301c5fb462a78eb51b191bd2dd'
  - url: 'https://git.kernel.org/stable/c/570af5db081b87374594a00711ac5760d2ea6844'
  - url: 'https://git.kernel.org/stable/c/ffaaff82336db84e9b58e7a3e81c2fd64e05ed7a'
  - url: 'https://git.kernel.org/stable/c/258ec63c0f281bf7b50f9de67c8e93b5b7be5ed4'
  - url: 'https://git.kernel.org/stable/c/3dcfb04dd43b16fa1240fc6487fff578ad57264c'
  - url: 'https://git.kernel.org/stable/c/db8407b9fd06d857a4a5e8bcff1d086d13007711'
  - url: 'https://git.kernel.org/stable/c/7ef78d71ca713d8c00f7c34ddcf276c808143f77'
tags:
  - cve.org
epss: 0.00171
epssPercentile: 0.06493
ingestedAt: '2026-11-06T16:57:43.148Z'
---

## Overview

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

KVM: VMX: Grab vmcs12 on CR8 interception update iff vCPU is in guest mode

When updating CR8 intercepts, get vmcs12 if and only if the vCPU is in
guest mode so that a future change can have update CR8 intercepts during
vCPU creation, without running afoul of get_vmcs12()'s lockdep assertion.

  ------------[ cut here ]------------
  debug_locks && !(lock_is_held(&(&vcpu->mutex)->dep_map) || !refcount_read(&vcpu->kvm->users_count))
  WARNING: arch/x86/kvm/vmx/nested.h:61 at get_vmcs12 arch/x86/kvm/vmx/nested.h:60 [inline], CPU#0: syz.2.19/5879
  WARNING: arch/x86/kvm/vmx/nested.h:61 at vmx_update_cr8_intercept+0x3de/0x4e0 arch/x86/kvm/vmx/vmx.c:6879, CPU#0: syz.2.19/5879
  Modules linked in:
  CPU: 0 UID: 0 PID: 5879 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT(full)
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
  RIP: 0010:get_vmcs12 arch/x86/kvm/vmx/nested.h:60 [inline]
  RIP: 0010:vmx_update_cr8_intercept+0x3de/0x4e0 arch/x86/kvm/vmx/vmx.c:6879
  Call Trace:
   <TASK>
   apic_update_ppr arch/x86/kvm/lapic.c:984 [inline]
   kvm_lapic_reset+0x1c24/0x2980 arch/x86/kvm/lapic.c:3023
   kvm_vcpu_reset+0x44c/0x1bf0 arch/x86/kvm/x86.c:12986
   kvm_arch_vcpu_create+0x746/0x8b0 arch/x86/kvm/x86.c:12847
   kvm_vm_ioctl_create_vcpu+0x428/0x930 virt/kvm/kvm_main.c:4201
   kvm_vm_ioctl+0x893/0xd50 virt/kvm/kvm_main.c:5159
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:597 [inline]
   __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
   </TASK>

No functional change intended.

## Affected

- `Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 < c7cd3605244c924249dea32632e1bc3e89bda543`
- `Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 < 9a21f1defd96c6301c5fb462a78eb51b191bd2dd`
- `Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 < 570af5db081b87374594a00711ac5760d2ea6844`
- `Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 < ffaaff82336db84e9b58e7a3e81c2fd64e05ed7a`
- `Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 < 258ec63c0f281bf7b50f9de67c8e93b5b7be5ed4`
- `Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 < 3dcfb04dd43b16fa1240fc6487fff578ad57264c`
- `Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 < db8407b9fd06d857a4a5e8bcff1d086d13007711`
- `Linux >= a7c0b07d570848e50fce4d31ac01313484d6b844 < 7ef78d71ca713d8c00f7c34ddcf276c808143f77`
- `Linux 3.18`

## Remediation

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