CVE-2016-9310
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 control mode (mode 6) functionality in ntpd in NTP before 4.2.8p9 allows remote attackers to set or unset traps via a crafted control mode packet.
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 control mode (mode 6) functionality in ntpd before version 4.2.8p9 contains a vulnerability that allows remote attackers to set or unset NTP traps via crafted control mode packets without proper authentication validation.
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<= 4.2.8CVSS 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
- Low
- Integrity
- None
- Availability
- Low
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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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Check if ntpd is installed and get its versionRun 'ntpd --version' or 'ntpdc --version' to display the installed NTP daemon version. On Linux systems, also try 'rpm -q ntp' or 'dpkg -l ntp' to list the package version.Affected if The installed version is 4.2.8 or earlier (any version <= 4.2.8)
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Verify the exact package version numberCheck the installed package details: 'rpm -qa | grep -i ntp' or 'dpkg --list | grep ntp' to see the full version string including any patch levels.Affected if The version string shows 4.2.8p8 or earlier, or shows 4.2.8 without a patch suffix (p9 or higher)
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Confirm ntpd service is running and listeningRun 'ps aux | grep ntpd' to verify the ntpd process is active, then run 'netstat -ulnp | grep 123' or 'ss -ulnp | grep 123' to confirm UDP port 123 is open.Affected if ntpd is running and port 123/UDP is exposed on a network interface
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Verify control mode (mode 6) is accessibleUse 'ntpdc -c sysinfo <ntp_server>' to test if the NTP control protocol responds. If authentication is not required (default in affected versions), the system will respond to mode 6 queries.Affected if The control mode query returns a response without requiring authentication, indicating the vulnerability is exploitable
The environment is affected if ntpd version 4.2.8 or earlier is installed and the service is running with control mode (mode 6) accessible on the 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 dataUpgrade ntpd to version 4.2.8p9 or later to remediate this vulnerability. If immediate patching is not possible, consider network segmentation to restrict unauthorized access to NTP service ports.
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-9310 — 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-2016-9310 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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