---
id: CVE-2021-33574
title: >-
  The mq_notify function in the GNU C Library (aka glibc) versions 2.32 and 2.33
  has a use-after-free
summary: >-
  The mq_notify function in the GNU C Library (aka glibc) versions 2.32 and 2.33
  has a use-after-free. It may use the notification thread attributes object
  (passed through its struct sigevent parameter) after it has been freed by the
  calle…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: gnu
product: glibc
affected:
  - glibc = 2.32
  - glibc = 2.33
  - fedora = 33
  - fedora = 34
  - cloud_backup
  - 'e-series_santricity_os_controller >= 11.0, <= 11.70.1'
  - solidfire_baseboard_management_controller_firmware
  - h300s_firmware
  - h500s_firmware
  - h700s_firmware
  - h300e_firmware
  - h500e_firmware
  - h700e_firmware
  - h410s_firmware
  - debian_linux = 10.0
published: '2021-05-25'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T12:17:12.520'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-33574'
references:
  - url: 'https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html'
    label: cve@mitre.org
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KJYYIMDDYOHTP2PORLABTOHYQYYREZDD/
    label: cve@mitre.org
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RBUUWUGXVILQXVWEOU7N42ICHPJNAEUP/
    label: cve@mitre.org
  - url: 'https://security.gentoo.org/glsa/202107-07'
    label: cve@mitre.org
  - url: 'https://security.netapp.com/advisory/ntap-20210629-0005/'
    label: cve@mitre.org
  - url: 'https://sourceware.org/bugzilla/show_bug.cgi?id=27896'
    label: cve@mitre.org
  - url: 'https://sourceware.org/bugzilla/show_bug.cgi?id=27896#c1'
    label: cve@mitre.org
  - url: 'https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KJYYIMDDYOHTP2PORLABTOHYQYYREZDD/
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RBUUWUGXVILQXVWEOU7N42ICHPJNAEUP/
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.gentoo.org/glsa/202107-07'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20210629-0005/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://sourceware.org/bugzilla/show_bug.cgi?id=27896'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://sourceware.org/bugzilla/show_bug.cgi?id=27896#c1'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-831302.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
epss: 0.02874
epssPercentile: 0.86481
ingestedAt: '2026-10-14T12:29:10.819Z'
---

## Overview

The mq_notify function in the GNU C Library (aka glibc) versions 2.32 and 2.33 has a use-after-free. It may use the notification thread attributes object (passed through its struct sigevent parameter) after it has been freed by the caller, leading to a denial of service (application crash) or possibly unspecified other impact.

## Affected

- `glibc = 2.32`
- `glibc = 2.33`
- `fedora = 33`
- `fedora = 34`
- `cloud_backup`
- `e-series_santricity_os_controller >= 11.0, <= 11.70.1`
- `solidfire_baseboard_management_controller_firmware`
- `h300s_firmware`
- `h500s_firmware`
- `h700s_firmware`
- `h300e_firmware`
- `h500e_firmware`
- `h700e_firmware`
- `h410s_firmware`
- `debian_linux = 10.0`

## Remediation

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