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Vulnerability record · CVE-2021-22946 · published 29 September 2021

CVE-2021-22946: Haxx curl cleartext transmission vulnerability

Haxx · Curl

A user can tell curl >= 7.20.0 and <= 7.78.0 to require a successful upgrade to TLS when speaking to an IMAP, POP3 or FTP server (`--ssl-reqd` on the command line or`CURLOPT_USE_SSL` set to `CURLUSESSL_CONTROL` or `CURLUSESSL_ALL` withlibcurl). This requirement could be bypassed if the server would return a properly crafted but perfectly legitimate response.This flaw would then make curl silently continue its operations **withoutTLS** contrary to the instructions and expectations, exposing possibly sensitive data in clear text over the network.

7.5 CVSS 3.1 High EPSS 4.5% · top 8.8% CWE-325 · CWE-325CWE-319 · Cleartext transmission
7.5CVSS 3.1 base score, v2 5.0
4.5%EPSS exploitation probability, 30 days
NoNot in CISA KEV
29Affected product versions listed by NVD
32References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

A user can tell curl >= 7.20.0 and <= 7.78.0 to require a successful upgrade to TLS when speaking to an IMAP, POP3 or FTP server (`--ssl-reqd` on the command line or`CURLOPT_USE_SSL` set to `CURLUSESSL_CONTROL` or `CURLUSESSL_ALL` withlibcurl). This requirement could be bypassed if the server would return a properly crafted but perfectly legitimate response.This flaw would then make curl silently continue its operations **withoutTLS** contrary to the instructions and expectations, exposing possibly sensitive data in clear text over the network.

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

Affected products

29 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/1334111 ExploitIssue TrackingPatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00022.html Mailing ListThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/08/msg00017.html Mailing ListThird 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://security.netapp.com/advisory/ntap-20220121-0008/ Third Party Advisory
https://support.apple.com/kb/HT213183 Release NotesThird Party Advisory
https://www.debian.org/security/2022/dsa-5197 Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html PatchThird 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/1334111 ExploitIssue TrackingPatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2021/09/msg00022.html Mailing ListThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/08/msg00017.html Mailing ListThird 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://security.netapp.com/advisory/ntap-20220121-0008/ Third Party Advisory
https://support.apple.com/kb/HT213183 Release NotesThird Party Advisory
https://www.debian.org/security/2022/dsa-5197 Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html PatchThird Party Advisory

Track CVE-2021-22946 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.

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

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Source: NIST National Vulnerability Database (record CVE-2021-22946), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.