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NtpApplication

CVE-2016-7433

MEDIUM · 5.3 CVSS v3.0 Published 2017-01-13
Fix available
A fix is available. Upgrade to after 4.2.8 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 · unedited
NTP before 4.2.8p9 does not properly perform the initial sync calculations, which allows remote attackers to unspecified impact via unknown vectors, related to a "root distance that did not include the peer dispersion."

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 · moderate confidence

NTP versions before 4.2.8p9 have a flaw in initial synchronization calculations where the root distance computation fails to include peer dispersion. This can cause incorrect time synchronization and potentially expose systems to time-based attacks during the initial sync phase.

MitigationUpgrade NTP to version 4.2.8p9 or later to include the proper peer dispersion in root distance calculations during initial synchronization.

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
NtpApplication
Affected:<= 4.2.8

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed NTP version
    Run 'ntpd --version' or 'ntpq --version' to determine the exact version of NTP daemon installed on the system
    Affected if Version is 4.2.8 or earlier (prior to 4.2.8p9)
  2. Confirm NTP daemon is active
    Check if ntpd service is running using 'systemctl status ntpd' or 'service ntpd status' depending on your system
    Affected if NTP daemon is actively running and performing time synchronization
  3. Verify initial synchronization status
    Execute 'ntpq -c rv' or 'ntpdc -c sysinfo' to check the system peer status and synchronization state, particularly looking for 'init' or recent sync indicators
    Affected if The system is in the initial synchronization phase (has not yet completed full synchronization)
  4. Compare version against affected range
    If version output shows only major.minor (e.g., 4.2.8), treat as the base release; verify it is not 4.2.8p9 or later which contains the fix
    Affected if Installed version is 4.2.8 or any version below 4.2.8p9

A system is affected if it runs NTP version 4.2.8 or earlier AND is currently performing or will perform initial time synchronization, as the root distance calculation lacks peer dispersion during that phase.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Upgrade available Upgrade to a release after 4.2.8
Interim mitigation

Upgrade NTP to version 4.2.8p9 or later to include the proper peer dispersion in root distance calculations during initial synchronization.

Fix this in Ntp Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-7433 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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