CVE-2016-9686
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 · uneditedThe Puppet Communications Protocol (PCP) Broker incorrectly validates message header sizes. An attacker could use this to crash the PCP Broker, preventing commands from being sent to agents. This is resolved in Puppet Enterprise 2016.4.3 and 2016.5.2.
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 confidenceThe Puppet Communications Protocol (PCP) Broker contains a validation flaw where message header sizes are not properly validated. An attacker can send specially crafted messages with malformed header sizes to trigger a crash of the PCP Broker, which prevents legitimate commands from being delivered to managed agents.
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>= 2016.4.0, < 2016.4.3= 2016.5.1CVSS 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
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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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Confirm PCP Broker is enabledCheck if the PCP Broker service is running. On Puppet Enterprise primary server, run: systemctl status pcp-broker or service pcp-broker statusAffected if PCP Broker service is active and listening on network ports (port 8142 by default)
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Determine installed Puppet Enterprise versionRun: puppet --version or check /opt/puppetlabs/puppet/VERSION on the primary serverAffected if Version is 2016.4.0 through 2016.4.2, or exactly 2016.5.1
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Verify PCP Broker network exposureCheck if port 8142 is open to network access using: netstat -tlnp | grep 8142 or ss -tlnp | grep 8142Affected if PCP Broker port 8142 is bound to a network interface accessible to untrusted systems
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Check for recent broker crashesReview PCP Broker logs in /var/log/puppetlabs/pcp-broker/ for repeated crash or connection reset entries around the time of potential attackAffected if Broker logs show unexpected restarts or malformed message errors
Environment is affected if PCP Broker is running and the Puppet Enterprise version falls within 2016.4.0 to 2016.4.2 or equals 2016.5.1, with the broker port exposed to network
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 data2016.4.3
Upgrade Puppet Enterprise to version 2016.4.3, 2016.5.2, or later to obtain the fixed PCP Broker code that properly validates message header sizes.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-9686 — 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-2016-9686 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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