CVE-2009-5009
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 · uneditedDouble free vulnerability in OpenConnect before 1.40 might allow remote AnyConnect SSL VPN servers to cause a denial of service (application crash) or possibly have unspecified other impact via a crafted DTLS Cipher option during a reconnect operation.
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 confidenceOpenConnect client before version 1.40 contains a double-free vulnerability in DTLS cipher handling. During a VPN reconnect operation, a malicious or compromised AnyConnect SSL VPN server can send a specially crafted DTLS Cipher option that triggers a double-free condition, causing client application crash or potentially enabling arbitrary code execution.
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<= 1.30= 1.00= 1.10= 1.20CVSS 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
- Low
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:N/A:P
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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Verify OpenConnect client is installedRun 'openconnect --version' or check package manager for openconnect packageAffected if OpenConnect is not installed on the system
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Determine installed OpenConnect versionRun 'openconnect --version' and capture the version number displayed (e.g., output like 'OpenConnect version v1.30')Affected if Version is 1.00, 1.10, 1.20, or any version <= 1.30 (versions prior to 1.40)
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Check if DTLS cipher support is enabledInspect OpenConnect configuration files (typically in /etc/openconnect or ~/.openconnect) or run 'openconnect --help' to see if DTLS-related options are present and configuredAffected if DTLS/DTLS cipher handling is actively configured for VPN connections
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Identify active or recent VPN reconnect sessionsCheck running processes for active openconnect sessions ('ps aux | grep openconnect') or review VPN connection logs for recent reconnect operationsAffected if An openconnect process is active or recent reconnect events are logged involving DTLS negotiation
A system is affected if OpenConnect client versions 1.00 through 1.30 are installed and DTLS cipher handling is enabled, particularly during active or recent VPN reconnect operations.
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 OpenConnect client to version 1.40 or later to receive the patched code. As this is a client-side vulnerability, organizations should ensure all VPN clients are updated before connecting to any VPN server.
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2009-5009 — 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-2009-5009 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
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