---
id: CVE-2021-46973
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: qrtr: Avoid potential use after free in MHI send

  It is possible that the MHI ul_callback will be invoked immediately
  following the queueing of the skb for transmi…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: qrtr: Avoid potential use after free in MHI send

  It is possible that the MHI ul_callback will be invoked immediately
  following the queueing of the skb for transmi…
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 >= 5.8, <=  5.10.35'
  - 'linux_kernel >= 5.11, <= 5.11.19'
  - 'linux_kernel >= 5.12, <= 5.12.2'
published: '2024-02-27'
updated: '2026-08-04'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-46973'
references:
  - url: 'https://git.kernel.org/stable/c/03c649dee8b1eb5600212a249542a70f47a5ab40'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/47a017f33943278570c072bc71681809b2567b3a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/48ec949ac979b4b42d740f67b6177797af834f80'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ea474054c2cc6e1284604b21361f475c7cc8c0a0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/03c649dee8b1eb5600212a249542a70f47a5ab40'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/47a017f33943278570c072bc71681809b2567b3a'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/48ec949ac979b4b42d740f67b6177797af834f80'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/ea474054c2cc6e1284604b21361f475c7cc8c0a0'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-46973.json
  - url: 'https://access.redhat.com/security/cve/CVE-2021-46973'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2266828'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2021-46973'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2021-46973'
  - url: >-
      https://lore.kernel.org/linux-cve-announce/2024022721-CVE-2021-46973-20ce@gregkh/T/#u
tags:
  - nvd
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00231
epssPercentile: 0.14102
ingestedAt: '2026-08-04T10:39:38.674Z'
scores:
  nvd: 7.8
  vendor: 5.5
---

## Overview

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

net: qrtr: Avoid potential use after free in MHI send

It is possible that the MHI ul_callback will be invoked immediately
following the queueing of the skb for transmission, leading to the
callback decrementing the refcount of the associated sk and freeing the
skb.

As such the dereference of skb and the increment of the sk refcount must
happen before the skb is queued, to avoid the skb to be used after free
and potentially the sk to drop its last refcount..

## Affected

- `linux_kernel >= 5.8, <=  5.10.35`
- `linux_kernel >= 5.11, <= 5.11.19`
- `linux_kernel >= 5.12, <= 5.12.2`

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8 · updated 2026-10-02 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-46973.json)