CVE-2016-2519
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 · uneditedntpd in NTP before 4.2.8p7 and 4.3.x before 4.3.92 allows remote attackers to cause a denial of service (ntpd abort) by a large request data value, which triggers the ctl_getitem function to return a NULL value.
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 confidenceIn NTP versions before 4.2.8p7 and 4.3.x before 4.3.92, the ntpd daemon contains a flaw in the ctl_getitem function where processing a large request data value causes the function to return a NULL pointer, leading to an ntpd abort and 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<= 4.2.8= 4.3.0= 4.3.1= 4.3.2= 4.3.3= 4.3.4= 4.3.5= 4.3.6= 4.3.7= 4.3.8= 4.3.9= 4.3.10CVSS 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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Verify ntpd is installedRun `ntpd --version` or check package manager: `rpm -q ntp` (RHEL/CentOS) or `dpkg -l ntp` (Debian/Ubuntu)Affected if ntpd is not installed - the system is not affected by this specific vulnerability in ntpd
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Determine the exact ntpd versionRun `ntpd --version` and note the full version string (e.g., 4.2.8p4, 4.3.5)Affected if Version is 4.2.8 or lower, or falls in the 4.3.0 through 4.3.91 range - the system is potentially affected
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Confirm ntpd process is runningRun `ps aux | grep ntpd` or `systemctl status ntpd` to verify the ntpd daemon is actively runningAffected if ntpd is not running - the denial of service condition cannot be triggered even with a vulnerable version
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Check if ntpd is listening on network interfacesRun `netstat -anp | grep 123` or `ss -anp | grep :123` to verify ntpd is bound to network ports (port 123/UDP)Affected if ntpd is exposed to network requests - remote attackers can trigger the large request that causes the NULL pointer crash
The system is affected if ntpd is running with a version <= 4.2.8 or between 4.3.0 and 4.3.91, and the daemon is accessible over the network to accept the malicious request.
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 4.2.8p7 or later (4.3.x branches: 4.3.92 or later) to patch the vulnerable ctl_getitem function. Network filtering can also limit exposure to untrusted NTP sources.
- Consultation1.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-2519 — 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-2016-2519 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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- Version or environment caveats, and links to real fixes
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