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Vulnerability record · CVE-2021-22924 · published 5 August 2021

CVE-2021-22924: Haxx libcurl improper input validation vulnerability

Haxx · Libcurl

libcurl keeps previously used connections in a connection pool for subsequenttransfers to reuse, if one of them matches the setup.Due to errors in the logic, the config matching function did not take 'issuercert' into account and it compared the involved paths *case insensitively*,which could lead to libcurl reusing wrong connections.File paths are, or can be, case sensitive on many systems but not all, and caneven vary depending on used file systems.The comparison also didn't include the 'issuer cert' which a transfer can setto qualify how to verify the server certificate.

3.7 CVSS 3.1 Low EPSS 6.3% · top 6.7% CWE-20 · Improper input validationCWE-706 · CWE-706
3.7CVSS 3.1 base score, v2 4.3
6.3%EPSS exploitation probability, 30 days
NoNot in CISA KEV
33Affected product versions listed by NVD
30References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

libcurl keeps previously used connections in a connection pool for subsequenttransfers to reuse, if one of them matches the setup.Due to errors in the logic, the config matching function did not take 'issuercert' into account and it compared the involved paths *case insensitively*,which could lead to libcurl reusing wrong connections.File paths are, or can be, case sensitive on many systems but not all, and caneven vary depending on used file systems.The comparison also didn't include the 'issuer cert' which a transfer can setto qualify how to verify the server certificate.

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

Affected products

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

References

LinkTags
https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf PatchThird Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-732250.pdf Third Party Advisory
https://hackerone.com/reports/1223565 ExploitIssue TrackingPatchThird Party Advisory
https://lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc%40%3Cdev.kafka.apache.org Mailing ListThird Party Advisory
https://lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc%40%3Cusers.kafka.apache.o Mailing ListThird Party Advisory
https://lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7%40%3Cdev.kafka.apache.org Mailing ListThird Party Advisory
https://lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7%40%3Cusers.kafka.apache.o Mailing ListThird Party Advisory
https://lists.debian.org/debian-lts-announce/2021/08/msg00017.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/FRUCW2UVNYUDZF72DQLFQR4 Mailing ListThird Party Advisory
https://security.netapp.com/advisory/ntap-20210902-0003/ Third Party Advisory
https://www.debian.org/security/2022/dsa-5197 Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html PatchThird Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf PatchThird Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-732250.pdf Third Party Advisory
https://hackerone.com/reports/1223565 ExploitIssue TrackingPatchThird Party Advisory
https://lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc%40%3Cdev.kafka.apache.org Mailing ListThird Party Advisory
https://lists.apache.org/thread.html/r61db8e7dcb56dc000a5387a88f7a473bacec5ee01b9ff3f55308aacc%40%3Cusers.kafka.apache.o Mailing ListThird Party Advisory
https://lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7%40%3Cdev.kafka.apache.org Mailing ListThird Party Advisory
https://lists.apache.org/thread.html/rbf4ce74b0d1fa9810dec50ba3ace0caeea677af7c27a97111c06ccb7%40%3Cusers.kafka.apache.o Mailing ListThird Party Advisory
https://lists.debian.org/debian-lts-announce/2021/08/msg00017.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/FRUCW2UVNYUDZF72DQLFQR4 Mailing ListThird Party Advisory
https://security.netapp.com/advisory/ntap-20210902-0003/ Third Party Advisory
https://www.debian.org/security/2022/dsa-5197 Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.html PatchThird Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.html PatchThird Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2021-22924), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.