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NtpApplication

CVE-2015-7979

HIGH · 7.5 CVSS v3.0 Published 2017-01-30
Fix available
A fix is available. Upgrade to after 4.2.8 or later.
See remediation →
84/100
Remediation priority · High
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 4.2.8p6 and 4.3.x before 4.3.90 allows remote attackers to cause a denial of service (client-server association tear down) by sending broadcast packets with invalid authentication to a broadcast client.

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 confidence

NTP versions before 4.2.8p6 and 4.3.x before 4.3.90 contain a denial-of-service vulnerability where remote attackers can send broadcast packets with invalid authentication to a broadcast client, causing the client-server association to tear down and disrupting time synchronization services.

MitigationUpgrade NTP to version 4.2.8p6 or later (or 4.3.90+ for the 4.3.x branch) to patch this vulnerability. Alternatively, disable NTP broadcast mode or implement proper authentication controls on broadcast listeners if upgrading is not immediately feasible.

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= 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= 4.3.10= 4.3.11

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
High

CVSS:3.0/AV:N/AC:L/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 checks

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

  1. Determine installed NTP version
    Run 'ntpdc -v' or 'ntpq --version' to obtain the NTP daemon version number
    Affected if Version is 4.2.8 or earlier, or is 4.3.0 through 4.3.11 (excluding 4.3.90 and later)
  2. Locate NTP configuration file
    Check /etc/ntp.conf or the active NTP config file for broadcast client settings
    Affected if Configuration file exists and is readable
  3. Verify if broadcast client mode is enabled
    Search the configuration file for the 'broadcastclient' directive or 'broadcast' entries that enable receiving broadcast packets
    Affected if The 'broadcastclient' directive is present, enabling the system to listen to NTP broadcast messages
  4. Check runtime broadcast client status
    Run 'ntpq -c rv' and look for 'broadcastclient' in the output to confirm if broadcast client mode is active at runtime
    Affected if Broadcast client mode is enabled in the running configuration

System is affected only if the installed NTP version falls within the vulnerable ranges (4.2.8 or earlier, or 4.3.0-4.3.11) AND broadcast client mode is enabled either in config or at runtime.

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 4.2.8p6 or later (or 4.3.90+ for the 4.3.x branch) to patch this vulnerability. Alternatively, disable NTP broadcast mode or implement proper authentication controls on broadcast listeners if upgrading is not immediately feasible.

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
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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-2015-7979 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