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PatchSiren cyber security CVE debrief

CVE-2015-7975 Ntp CVE debrief

CVE-2015-7975 is a denial-of-service vulnerability in NTP's nextvar function. The issue was publicly recorded by NVD on 2017-01-30 and applies to NTP versions before 4.2.8p6 and 4.3.x before 4.3.90. The defect is an input-length validation problem that can trigger an application crash, so the main operational risk is service disruption rather than data exposure.

Vendor
Ntp
Product
CVE-2015-7975
CVSS
MEDIUM 6.2
CISA KEV
Not listed in stored evidence
Original CVE published
2017-01-30
Original CVE updated
2026-05-13
Advisory published
2017-01-30
Advisory updated
2026-05-13

Who should care

Administrators and operators running affected NTP daemons, especially systems that rely on precise time synchronization and cannot tolerate ntpd crashes or restarts. Security teams responsible for Linux/Unix fleet patching should also care because the NVD record includes multiple downstream vendor advisories and package updates.

Technical summary

NVD describes the flaw as improper validation of input length in the nextvar function. The weakness is classified as CWE-119, and the published CVSS v3.0 vector is AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, indicating a local attack path with high availability impact. The vulnerability is addressed in NTP releases after 4.2.8p6 and 4.3.x after 4.3.90.

Defensive priority

Medium. The issue is a crash-triggering bug with availability impact only, but it affects a foundational time service and is documented in official and downstream advisories. Remediation is important wherever ntpd stability is operationally critical.

Recommended defensive actions

  • Upgrade NTP to a fixed release at or beyond 4.2.8p6 or 4.3.90, depending on your branch.
  • Review downstream vendor advisories and package updates for your distribution or appliance platform.
  • Validate whether any fleet systems are still running affected NTP branches before scheduling maintenance.
  • Monitor NTP service health and restart behavior on systems where patching must be staged.
  • Prefer vendor-maintained packages or security advisories when applying fixes to embedded or appliance deployments.

Evidence notes

This debrief is based on the NVD CVE record and the linked vendor/downstream references included in the source corpus. The vulnerability description explicitly states that nextvar in NTP before 4.2.8p6 and 4.3.x before 4.3.90 does not properly validate input length and can cause a denial of service via application crash. NVD also classifies the weakness as CWE-119 and lists a CVSS v3.0 vector with high availability impact. The presence of multiple downstream advisories in the references supports that the issue was broadly remediated across distributions.

Official resources

Publicly recorded in the CVE/NVD ecosystem on 2017-01-30. The source corpus indicates the issue had downstream advisories and vendor references by 2016, but this debrief uses the CVE published date for disclosure timing.