---
id: CVE-2021-47061
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  KVM: Destroy I/O bus devices on unregister failure _after_ sync'ing SRCU

  If allocating a new instance of an I/O bus fails when unregistering a
  device, wait to destroy …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  KVM: Destroy I/O bus devices on unregister failure _after_ sync'ing SRCU

  If allocating a new instance of an I/O bus fails when unregistering a
  device, wait to destroy …
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.9, < 5.10.37'
  - 'linux_kernel >= 5.11, < 5.11.21'
  - 'linux_kernel >= 5.12, < 5.12.4'
patched:
  - linux_kernel 5.12.4
published: '2024-02-29'
updated: '2026-08-04'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-47061'
references:
  - url: 'https://git.kernel.org/stable/c/03c6cccedd3913006744faa252a4da5145299343'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2ee3757424be7c1cd1d0bbfa6db29a7edd82a250'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/30f46c6993731efb2a690c9197c0fd9ed425da2d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4e899ca848636b37e9ac124bc1723862a7d7d927'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/03c6cccedd3913006744faa252a4da5145299343'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/2ee3757424be7c1cd1d0bbfa6db29a7edd82a250'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/30f46c6993731efb2a690c9197c0fd9ed425da2d'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/4e899ca848636b37e9ac124bc1723862a7d7d927'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00241
epssPercentile: 0.1355
ingestedAt: '2026-08-04T10:39:39.804Z'
---

## Overview

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

KVM: Destroy I/O bus devices on unregister failure _after_ sync'ing SRCU

If allocating a new instance of an I/O bus fails when unregistering a
device, wait to destroy the device until after all readers are guaranteed
to see the new null bus.  Destroying devices before the bus is nullified
could lead to use-after-free since readers expect the devices on their
reference of the bus to remain valid.

## Affected

- `linux_kernel >= 5.9, < 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`