---
id: CVE-2021-47035
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  iommu/vt-d: Remove WO permissions on second-level paging entries

  When the first level page table is used for IOVA translation, it only
  supports Read-Only and Read-Writ…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  iommu/vt-d: Remove WO permissions on second-level paging entries

  When the first level page table is used for IOVA translation, it only
  supports Read-Only and Read-Writ…
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 >= 5.6, < 5.10.37'
  - 'linux_kernel >= 5.11, < 5.11.21'
  - 'linux_kernel >= 5.12, < 5.12.4'
patched:
  - linux_kernel 5.12.4
published: '2024-02-28'
updated: '2026-08-04'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-47035'
references:
  - url: 'https://git.kernel.org/stable/c/25faff78138933244c678c7fc78f7c0340fa04a0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/66c24699f266ff310381a9552d3576eea8ad6e20'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/89bd620798704a8805fc9db0d71d7f812cf5b3d2'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/eea53c5816889ee8b64544fa2e9311a81184ff9c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/25faff78138933244c678c7fc78f7c0340fa04a0'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/66c24699f266ff310381a9552d3576eea8ad6e20'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/89bd620798704a8805fc9db0d71d7f812cf5b3d2'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/c848416cc05afc1589edba04fe00b85c2f797ee3'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/eea53c5816889ee8b64544fa2e9311a81184ff9c'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00256
epssPercentile: 0.1542
ingestedAt: '2026-08-04T10:39:39.448Z'
---

## Overview

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

iommu/vt-d: Remove WO permissions on second-level paging entries

When the first level page table is used for IOVA translation, it only
supports Read-Only and Read-Write permissions. The Write-Only permission
is not supported as the PRESENT bit (implying Read permission) should
always set. When using second level, we still give separate permissions
that allows WriteOnly which seems inconsistent and awkward. We want to
have consistent behavior. After moving to 1st level, we don't want things
to work sometimes, and break if we use 2nd level for the same mappings.
Hence remove this configuration.

## Affected

- `linux_kernel >= 5.6, < 5.10.37`
- `linux_kernel >= 5.11, < 5.11.21`
- `linux_kernel >= 5.12, < 5.12.4`

## Remediation

Upgrade past the affected range:

- `linux_kernel 5.12.4`