OpenvpnApplication
CVE-2021-3606
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedOpenVPN before version 2.5.3 on Windows allows local users to load arbitrary dynamic loadable libraries via an OpenSSL configuration file if present, which allows the user to run arbitrary code with the same privilege level as the main OpenVPN process (openvpn.exe).
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceOpenVPN versions before 2.5.3 on Windows are vulnerable to local privilege escalation via OpenSSL configuration file manipulation. A local attacker can specify an arbitrary DLL path in the OpenSSL configuration file, causing OpenVPN to load and execute malicious code with the same privilege level as the openvpn.exe process.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
OpenvpnApplication
< 2.5.3CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check installed OpenVPN version on WindowsOpen Programs and Features (appwiz.cpl) or check Program Files for OpenVPN version, or run 'openvpn --version' if in PATHAffected if version is lower than 2.5.3
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Confirm Windows operating systemVerify the target system is running Windows (this vulnerability only affects Windows)Affected if system is running Windows
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Locate OpenSSL configuration filesFind openssl.cnf or openssl.cfg files in OpenVPN directories (common locations: %ProgramFiles%\OpenVPN, %ProgramFiles%\OpenVPN\config, or system OpenSSL paths)Affected if OpenSSL configuration files exist in accessible locations
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Check file permissions on OpenSSL config filesRight-click the OpenSSL config file, go to Properties > Security, or use icacls command to review which users have Write or Full Control permissionsAffected if non-privileged users have Write or Full Control permissions on the OpenSSL config file
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Check for active or recent OpenVPN process activityOpen Task Manager or run 'tasklist | findstr openvpn' to check if openvpn.exe is running, or check event logs for OpenVPN service activityAffected if OpenVPN has been running on the system
A system is affected if OpenVPN version is below 2.5.3 on Windows and the OpenVPN process runs with elevated privileges while non-privileged users can write to OpenSSL configuration files.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data2.5.3
Upgrade OpenVPN installations on Windows to version 2.5.3 or later to obtain the patched version of the OpenSSL integration. Additionally, restrict write access to OpenSSL configuration files to privileged users only.
Fix this in Openvpn
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,904.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-3606 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-3606 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data