---
id: CVE-2023-53205
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  KVM: s390/diag: fix racy access of physical cpu number in diag 9c handler

  We do check for target CPU == -1, but this might change at the time we
  are going to use it
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  KVM: s390/diag: fix racy access of physical cpu number in diag 9c handler

  We do check for target CPU == -1, but this might change at the time we
  are going to use it. H…
severity: high
cvss: 7.3
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:H'
cwe:
  - CWE-787
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.13, < 5.15.121'
  - 'linux_kernel >= 5.16, < 6.1.39'
  - 'linux_kernel >= 6.2, < 6.4.4'
patched:
  - linux_kernel 6.4.4
published: '2025-09-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:17:39.427'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2023-53205'
references:
  - url: 'https://git.kernel.org/stable/c/0bc380beb78aa352eadbc21d934dd9606fcee808'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/86bfb18bad60fc468e5f112cbbd918462a8dd435'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a9ccf140a2a03a0ae82be4bdfbdd17bdaea72ff5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/dc7e0192c470a53d847c79a2796f9ac429477a26'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
epss: 0.0017
epssPercentile: 0.06304
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-15T21:34:27.370447Z'
ingestedAt: '2026-10-15T22:48:25.402Z'
---

## Overview

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

KVM: s390/diag: fix racy access of physical cpu number in diag 9c handler

We do check for target CPU == -1, but this might change at the time we
are going to use it. Hold the physical target CPU in a local variable to
avoid out-of-bound accesses to the cpu arrays.

## Affected

- `linux_kernel >= 5.13, < 5.15.121`
- `linux_kernel >= 5.16, < 6.1.39`
- `linux_kernel >= 6.2, < 6.4.4`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.4.4`