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LinuxOperating system · Oracle

CVE-2015-7977

MEDIUM · 5.9 CVSS v3.1 Published 2017-01-30
Fix available
A fix is available. Upgrade to 4.3.90 or later.
See remediation →
68/100
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
ntpd in NTP before 4.2.8p6 and 4.3.x before 4.3.90 allows remote attackers to cause a denial of service (NULL pointer dereference) via a ntpdc reslist command.

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

The NTP daemon (ntpd) contains a NULL pointer dereference vulnerability in versions before 4.2.8p6 and 4.3.x before 4.3.90. Attackers can trigger this by sending a crafted ntpdc reslist command, causing the daemon to crash and resulting in a denial of service.

MitigationUpgrade ntpd to version 4.2.8p6 or later / 4.3.90 or later. If immediate upgrading is not feasible, restrict network access to the NTP service to prevent unauthenticated attackers from sending the malicious ntpdc command.

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
LinuxOperating system
Affected:= 6
FreeBSDOperating system
Affected:= 9.3= 10.1= 10.2
FedoraOperating system
Affected:= 22= 23
Debian LinuxOperating system
Affected:= 8.0= 9.0
Ubuntu LinuxOperating system
Affected:= 12.04= 14.04= 16.04
NtpApplication
Affected:<= 4.2.8>= 4.3.0, < 4.3.90= 4.2.8
Tim 4r Ie FirmwareOperating system
Affected:all versions
Tim 4r Ie Dnp3 FirmwareOperating system
Affected:all versions

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
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/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 checks

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

  1. Identify if ntpd is installed
    Run 'ntpd --version' or 'ntpdc -V' to check if the NTP daemon is present on the system
    Affected if ntpd is not installed - the system is not affected by this specific vulnerability
  2. Check the installed ntpd version
    Execute 'ntpd --version' or check the package manager (dpkg -r, rpm -qi ntp) to determine the exact version number
    Affected if The version is less than 4.2.8p6, or is 4.3.0 through 4.3.89, indicating the vulnerability is present
  3. Verify ntpdc utility is available
    Check if the ntpdc command exists on the system by running 'which ntpdc' or 'ntpdc --version'
    Affected if ntpdc is not available - the specific attack vector using 'ntpdc reslist' cannot be executed
  4. Confirm ntpd is network-listening
    Run 'netstat -anp | grep 123' or 'ss -anp | grep 123' to see if ntpd is bound to network interfaces (not only localhost)
    Affected if ntpd is exposed to network access - remote attackers can send the malicious ntpdc reslist command to trigger the crash

The system is affected if ntpd is installed with a vulnerable version (before 4.2.8p6 or 4.3.0-4.3.89), ntpdc is available, and ntpd listens on accessible network ports allowing remote attackers to send the crafted reslist command.

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 4.3.90 or later
Fixed in 4.3.90
Interim mitigation

Upgrade ntpd to version 4.2.8p6 or later / 4.3.90 or later. If immediate upgrading is not feasible, restrict network access to the NTP service to prevent unauthenticated attackers from sending the malicious ntpdc command.

Fix this in Linux Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.

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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-2015-7977 in production — separate from our analysis above.

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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
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