CVE-2021-3547: High severity OpenVPN OpenVPN vulnerability
OpenVPN 3 Core Library version 3.6 and 3.6.1 allows a man-in-the-middle attacker to bypass the certificate authentication by issuing an unrelated server certificate using the same hostname found in the verify-x509-name option in a client configuration.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
Review OpenVPN client configurations that use the verify-x509-name option and ensure hostname verification is not bypassable by issuing an unrelated server certificate with the same hostname.
Event History
Frequently Asked Questions
What is CVE-2021-3547?
CVE-2021-3547 is a vulnerability in OpenVPN 3 Core Library version 3.6 and 3.6.1 that allows a man-in-the-middle attacker to bypass certificate authentication.
What is the severity of CVE-2021-3547?
The severity of CVE-2021-3547 is high with a CVSS score of 7.4.
How does CVE-2021-3547 work?
CVE-2021-3547 allows a man-in-the-middle attacker to bypass certificate authentication by issuing an unrelated server certificate using the same hostname found in the verify-x509-name option in a client configuration.
Which versions of OpenVPN are affected by CVE-2021-3547?
OpenVPN 3 Core Library versions 3.6 and 3.6.1 are affected by CVE-2021-3547.
Is there a fix for CVE-2021-3547?
Yes, OpenVPN has released a fix for CVE-2021-3547. It is recommended to upgrade to the latest version of OpenVPN.