---
id: CVE-2026-43427
title: 'usb: class: cdc-wdm: fix reordering issue in read code path'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  usb: class: cdc-wdm: fix reordering issue in read code path

  Quoting the bug report:

  Due to compiler optimization or CPU out-of-order execution, the
  desc->length updat…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 <
    638328ca9c17ae6511ad62198c57bae32ffa3c91
  - >-
    Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 <
    170e8daca24da6edb4be82ab01abf44e87af387b
  - >-
    Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 <
    c8fa96ed021923dae147bcd9f9205b8df7b82360
  - >-
    Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 <
    4ee3062bf2c9a722afef429826e8607eaf3fc6a0
  - >-
    Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 <
    276aef0fd2b92f41b920ac891c72cadeee957934
  - >-
    Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 <
    67ed312124bb1b61858778ac0b985b48961c862a
  - >-
    Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 <
    e3c874b05901dc519054b5107d16620e6d2b5fea
  - >-
    Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 <
    8df672bfe3ec2268c2636584202755898e547173
  - Linux 2.6.26
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T15:38:09.164948Z'
published: '2026-05-08'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T15:42:53.217Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-43427'
references:
  - url: 'https://git.kernel.org/stable/c/638328ca9c17ae6511ad62198c57bae32ffa3c91'
  - url: 'https://git.kernel.org/stable/c/170e8daca24da6edb4be82ab01abf44e87af387b'
  - url: 'https://git.kernel.org/stable/c/c8fa96ed021923dae147bcd9f9205b8df7b82360'
  - url: 'https://git.kernel.org/stable/c/4ee3062bf2c9a722afef429826e8607eaf3fc6a0'
  - url: 'https://git.kernel.org/stable/c/276aef0fd2b92f41b920ac891c72cadeee957934'
  - url: 'https://git.kernel.org/stable/c/67ed312124bb1b61858778ac0b985b48961c862a'
  - url: 'https://git.kernel.org/stable/c/e3c874b05901dc519054b5107d16620e6d2b5fea'
  - url: 'https://git.kernel.org/stable/c/8df672bfe3ec2268c2636584202755898e547173'
tags:
  - cve.org
epss: 0.00132
epssPercentile: 0.02817
ingestedAt: '2026-11-06T15:54:03.919Z'
---

## Overview

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

usb: class: cdc-wdm: fix reordering issue in read code path

Quoting the bug report:

Due to compiler optimization or CPU out-of-order execution, the
desc->length update can be reordered before the memmove. If this
happens, wdm_read() can see the new length and call copy_to_user() on
uninitialized memory. This also violates LKMM data race rules [1].

Fix it by using WRITE_ONCE and memory barriers.

## Affected

- `Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 < 638328ca9c17ae6511ad62198c57bae32ffa3c91`
- `Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 < 170e8daca24da6edb4be82ab01abf44e87af387b`
- `Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 < c8fa96ed021923dae147bcd9f9205b8df7b82360`
- `Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 < 4ee3062bf2c9a722afef429826e8607eaf3fc6a0`
- `Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 < 276aef0fd2b92f41b920ac891c72cadeee957934`
- `Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 < 67ed312124bb1b61858778ac0b985b48961c862a`
- `Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 < e3c874b05901dc519054b5107d16620e6d2b5fea`
- `Linux >= afba937e540c902c989cd516fd97ea0c8499bb27 < 8df672bfe3ec2268c2636584202755898e547173`
- `Linux 2.6.26`

## Remediation

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