---
id: CVE-2021-22945
title: >-
  When sending data to an MQTT server, libcurl <= 7.73.0 and 7.78.0 could in
  some circumstances erroneously keep a pointer to an already freed memory area
  and both use that again in a subsequent call to send data and also free it
  *again*.
summary: >-
  When sending data to an MQTT server, libcurl <= 7.73.0 and 7.78.0 could in
  some circumstances erroneously keep a pointer to an already freed memory area
  and both use that again in a subsequent call to send data and also free it
  *again*.
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
cwe:
  - CWE-415
  - CWE-415
  - CWE-415
vendor: haxx
product: libcurl
affected:
  - 'libcurl >= 7.73.0, <= 7.78.0'
  - fedora = 33
  - fedora = 35
  - cloud_backup
  - clustered_data_ontap
  - 'mysql_server >= 5.7.0, <= 5.7.35'
  - 'mysql_server >= 8.0.0, <= 8.0.26'
  - h300s_firmware
  - h500s_firmware
  - h700s_firmware
  - h300e_firmware
  - h500e_firmware
  - h700e_firmware
  - h410s_firmware
  - solidfire_baseboard_management_controller_firmware
  - 'macos >= 12.0.0, < 12.3'
  - sinec_ins < 1.0.1.1
  - debian_linux = 11.0
  - 'universal_forwarder >= 8.2.0, < 8.2.12'
  - 'universal_forwarder >= 9.0.0, < 9.0.6'
  - universal_forwarder = 9.1.0
patched:
  - macos 12.3
  - sinec_ins 1.0.1.1
  - universal_forwarder 9.0.6
published: '2021-09-23'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T12:17:08.693'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-22945'
references:
  - url: 'http://seclists.org/fulldisclosure/2022/Mar/29'
    label: support@hackerone.com
  - url: 'https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf'
    label: support@hackerone.com
  - url: 'https://hackerone.com/reports/1269242'
    label: support@hackerone.com
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/APOAK4X73EJTAPTSVT7IRVDMUWVXNWGD/
    label: support@hackerone.com
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RWLEC6YVEM2HWUBX67SDGPSY4CQB72OE/
    label: support@hackerone.com
  - url: 'https://security.gentoo.org/glsa/202212-01'
    label: support@hackerone.com
  - url: 'https://security.netapp.com/advisory/ntap-20211029-0003/'
    label: support@hackerone.com
  - url: 'https://support.apple.com/kb/HT213183'
    label: support@hackerone.com
  - url: 'https://www.debian.org/security/2022/dsa-5197'
    label: support@hackerone.com
  - url: 'https://www.oracle.com/security-alerts/cpuoct2021.html'
    label: support@hackerone.com
  - url: 'http://seclists.org/fulldisclosure/2022/Mar/29'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://hackerone.com/reports/1269242'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/APOAK4X73EJTAPTSVT7IRVDMUWVXNWGD/
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RWLEC6YVEM2HWUBX67SDGPSY4CQB72OE/
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.gentoo.org/glsa/202212-01'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20211029-0003/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://support.apple.com/kb/HT213183'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.debian.org/security/2022/dsa-5197'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.oracle.com/security-alerts/cpuoct2021.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-389290.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
epss: 0.06677
epssPercentile: 0.93762
ingestedAt: '2026-10-14T12:29:10.826Z'
---

## Overview

When sending data to an MQTT server, libcurl <= 7.73.0 and 7.78.0 could in some circumstances erroneously keep a pointer to an already freed memory area and both use that again in a subsequent call to send data and also free it *again*.

## Affected

- `libcurl >= 7.73.0, <= 7.78.0`
- `fedora = 33`
- `fedora = 35`
- `cloud_backup`
- `clustered_data_ontap`
- `mysql_server >= 5.7.0, <= 5.7.35`
- `mysql_server >= 8.0.0, <= 8.0.26`
- `h300s_firmware`
- `h500s_firmware`
- `h700s_firmware`
- `h300e_firmware`
- `h500e_firmware`
- `h700e_firmware`
- `h410s_firmware`
- `solidfire_baseboard_management_controller_firmware`
- `macos >= 12.0.0, < 12.3`
- `sinec_ins < 1.0.1.1`
- `debian_linux = 11.0`
- `universal_forwarder >= 8.2.0, < 8.2.12`
- `universal_forwarder >= 9.0.0, < 9.0.6`
- `universal_forwarder = 9.1.0`

## Remediation

Upgrade past the affected range:

- `macos 12.3`
- `sinec_ins 1.0.1.1`
- `universal_forwarder 9.0.6`