OpenvpnApplication
CVE-2017-7521
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 versions before 2.4.3 and before 2.3.17 are vulnerable to remote denial-of-service due to memory exhaustion caused by memory leaks and double-free issue in extract_x509_extension().
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 2.4.3 and before 2.3.17 contain memory leaks and a double-free vulnerability in the extract_x509_extension() function. Remote attackers can trigger this flaw to cause memory exhaustion, resulting in denial of service.
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
<= 2.3.16= 2.4.0= 2.4.1= 2.4.2CVSS 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
- Network
- Complexity
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/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 versionRun 'openvpn --version' or 'openvpn -v' to display version informationAffected if Version is 2.4.0, 2.4.1, 2.4.2, or any 2.3.x version 2.3.16 or earlier
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Verify X.509 certificate authentication is in useInspect OpenVPN server or client configuration file (typically in /etc/openvpn/ or specified via --config) for 'cert' directive pointing to an X.509 certificate, or check for presence of .crt/.key filesAffected if OpenVPN is configured to use certificate-based authentication with X.509 certificates
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Check for x509 attribute extraction configurationSearch configuration files for directives that trigger extract_x509_extension() usage, such as 'x509username', 'x509attr', 'verify-x509-name', or plugin configurations that process certificate extensionsAffected if Configuration includes any x509-related attribute extraction or username derivation from certificate extensions
If OpenVPN version is 2.4.0-2.4.2 or 2.3.16 or earlier AND the server or client processes X.509 certificate extensions via extract_x509_extension(), the environment is affected by this vulnerability.
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 dataUpgrade OpenVPN to version 2.4.3 or later (or 2.3.17 or later for the 2.3.x branch) to address the memory leak and double-free issues in extract_x509_extension().
Fix this in Openvpn
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 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 $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-7521 — 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-2017-7521 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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- 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