---
id: CVE-2026-23425
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  KVM: arm64: Fix ID register initialization for non-protected pKVM guests

  In protected mode, the hypervisor maintains a separate instance of
  the `kvm` structure for eac…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  KVM: arm64: Fix ID register initialization for non-protected pKVM guests

  In protected mode, the hypervisor maintains a separate instance of
  the `kvm` structure for eac…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 6.14.1, < 6.18.17'
  - 'linux_kernel >= 6.19, < 6.19.7'
  - linux_kernel = 6.14
  - linux_kernel = 7.0
patched:
  - linux_kernel 6.19.7
published: '2026-04-03'
updated: '2026-07-21'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-23425'
references:
  - url: 'https://git.kernel.org/stable/c/7e7c2cf0024d89443a7af52e09e47b1fe634ab17'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/858620655c1fbff05997e162fc7d83a3293d5142'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/bce3847f7c51b86332bf2e554c9e80ca3820f16c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00119
epssPercentile: 0.01572
ingestedAt: '2026-07-21T19:53:39.517Z'
---

## Overview

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

KVM: arm64: Fix ID register initialization for non-protected pKVM guests

In protected mode, the hypervisor maintains a separate instance of
the `kvm` structure for each VM. For non-protected VMs, this structure is
initialized from the host's `kvm` state.

Currently, `pkvm_init_features_from_host()` copies the
`KVM_ARCH_FLAG_ID_REGS_INITIALIZED` flag from the host without the
underlying `id_regs` data being initialized. This results in the
hypervisor seeing the flag as set while the ID registers remain zeroed.

Consequently, `kvm_has_feat()` checks at EL2 fail (return 0) for
non-protected VMs. This breaks logic that relies on feature detection,
such as `ctxt_has_tcrx()` for TCR2_EL1 support. As a result, certain
system registers (e.g., TCR2_EL1, PIR_EL1, POR_EL1) are not
saved/restored during the world switch, which could lead to state
corruption.

Fix this by explicitly copying the ID registers from the host `kvm` to
the hypervisor `kvm` for non-protected VMs during initialization, since
we trust the host with its non-protected guests' features. Also ensure
`KVM_ARCH_FLAG_ID_REGS_INITIALIZED` is cleared initially in
`pkvm_init_features_from_host` so that `vm_copy_id_regs` can properly
initialize them and set the flag once done.

## Affected

- `linux_kernel >= 6.14.1, < 6.18.17`
- `linux_kernel >= 6.19, < 6.19.7`
- `linux_kernel = 6.14`
- `linux_kernel = 7.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.19.7`