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Vulnerability record · CVE-2021-22945 · published 23 September 2021

CVE-2021-22945: Haxx libcurl double free vulnerability

Haxx · Libcurl

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*.

9.1 CVSS 3.1 Critical EPSS 6.7% · top 6.3% CWE-415 · Double free
9.1CVSS 3.1 base score, v2 5.8
6.7%EPSS exploitation probability, 30 days
NoNot in CISA KEV
17Affected product versions listed by NVD
20References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

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*.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected products

17 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://seclists.org/fulldisclosure/2022/Mar/29 Mailing ListThird Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf PatchThird Party Advisory
https://hackerone.com/reports/1269242 ExploitPatchThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/APOAK4X73EJTAPTSVT7IRVD Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RWLEC6YVEM2HWUBX67SDGPS Mailing ListThird Party Advisory
https://security.gentoo.org/glsa/202212-01 Third Party Advisory
https://security.netapp.com/advisory/ntap-20211029-0003/ Third Party Advisory
https://support.apple.com/kb/HT213183 Third Party Advisory
https://www.debian.org/security/2022/dsa-5197 Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html PatchThird Party Advisory
http://seclists.org/fulldisclosure/2022/Mar/29 Mailing ListThird Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf PatchThird Party Advisory
https://hackerone.com/reports/1269242 ExploitPatchThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/APOAK4X73EJTAPTSVT7IRVD Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RWLEC6YVEM2HWUBX67SDGPS Mailing ListThird Party Advisory
https://security.gentoo.org/glsa/202212-01 Third Party Advisory
https://security.netapp.com/advisory/ntap-20211029-0003/ Third Party Advisory
https://support.apple.com/kb/HT213183 Third Party Advisory
https://www.debian.org/security/2022/dsa-5197 Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html PatchThird Party Advisory

Track CVE-2021-22945 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-22945), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.