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Fencer Vulns
high 7.5

CVE-2016-7426 in the critical feed json

NTP before 4.2.8p9 rate limits responses received from the configured sources when rate limiting for all associations is enabled, which all…

published 2017-01-13 9 y ago modified 2026-06-17 4 mo ago also EUVD-2016-8279

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
12.4%
EPSS 12.4% chance of exploitation in 30 days, percentile 96%
public exploits
0
none known

Summary

NTP before 4.2.8p9 rate limits responses received from the configured sources when rate limiting for all associations is enabled, which allows remote attackers to cause a denial of service (prevent responses from the sources) by sending responses with a spoofed source address.

Patch / fix

  • ntp ntp 4.2.8, 4.3.94
  • hpe hpux-ntp c.4.2.8.2.0
  • ntp Debian 11 1:4.2.8p9+dfsg-1

debian advisories DEBIAN-CVE-2016-7426

  • ntp Ubuntu 14.04 LTS 1:4.2.6.p5+dfsg-3ubuntu2.14.04.11
  • ntp Ubuntu 16.04 LTS 1:4.2.8p4+dfsg-3ubuntu5.5

ubuntu advisories UBUNTU-CVE-2016-7426

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • ntp RHEL 6 4.2.6p5-10.el6_8.2
  • ntp RHEL 7 4.2.6p5-25.el7_3.1
  • sntp RHEL 7 4.2.6p5-25.el7_3.1
  • ntpdate RHEL 6 4.2.6p5-10.el6_8.2
  • ntpdate RHEL 7 4.2.6p5-25.el7_3.1
  • ntp-perl RHEL 6 4.2.6p5-10.el6_8.2
  • ntp-perl RHEL 7 4.2.6p5-25.el7_3.1

red hat advisories RHSA-2017:0252

  • ntp SLES 11 SP3-TERADATA, SLES 11 SP3-LTSS, SLES 11 SP2-LTSS +4 more 4.2.8p9-48.9.1
  • ntp SLES for SAP 12 SP2, SLES for SAP 12 SP1, SLES for Raspberry Pi 12 SP2 +4 more 4.2.8p9-55.1
  • ntp SLES for SAP 11 SP4, SLES 11 SP4 4.2.8p9-57.2
  • ntp SLES for SAP 12, SLES 12-LTSS 4.2.8p9-46.18.1

suse advisories SUSE-SU-2017:0255-1SUSE-SU-2016:3195-1SUSE-SU-2016:3196-1SUSE-SU-2016:3193-1

  • ntp openSUSE Tumbleweed 4.2.8p9-1.1

opensuse advisories openSUSE-SU-2024:10181-1

  • ntp Arch Linux 4.2.8.p9-1

arch linux advisories AVG-79AVG-80

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-7426 updated cvss 5.9

ntp: Client rate limiting and server responses

  • Red Hat Enterprise Linux 5 ntp
    affected: workaround, no fix planned “If you choose to use restrict default limited ..., be sure to use restrict source ... (without limited) to avoid this attack.”
  • Red Hat Enterprise Linux Client (v. 7) ntp 4.2.6p5-25.el7_3.1, ntpdate 4.2.6p5-25.el7_3.1 Red Hat Enterprise Linux Client Optional (v. 7) sntp 4.2.6p5-25.el7_3.1, ntp-perl 4.2.6p5-25.el7_3.1 Red Hat Enterprise Linux ComputeNode (v. 7) ntp 4.2.6p5-25.el7_3.1, ntpdate 4.2.6p5-25.el7_3.1 Red Hat Enterprise Linux ComputeNode Optional (v. 7) sntp 4.2.6p5-25.el7_3.1, ntp-perl 4.2.6p5-25.el7_3.1 Red Hat Enterprise Linux Desktop (v. 6) ntp 4.2.6p5-10.el6_8.2, ntpdate 4.2.6p5-10.el6_8.2 Red Hat Enterprise Linux Desktop Optional (v. 6) ntp-perl 4.2.6p5-10.el6_8.2
    +10 more products
    Red Hat Enterprise Linux HPC Node (v. 6) ntp 4.2.6p5-10.el6_8.2, ntpdate 4.2.6p5-10.el6_8.2 Red Hat Enterprise Linux HPC Node Optional (v. 6) ntp-perl 4.2.6p5-10.el6_8.2 Red Hat Enterprise Linux Server (v. 6) ntp 4.2.6p5-10.el6_8.2, ntpdate 4.2.6p5-10.el6_8.2 Red Hat Enterprise Linux Server (v. 7) ntp 4.2.6p5-25.el7_3.1, ntpdate 4.2.6p5-25.el7_3.1 Red Hat Enterprise Linux Server Optional (v. 6) ntp-perl 4.2.6p5-10.el6_8.2 Red Hat Enterprise Linux Server Optional (v. 7) sntp 4.2.6p5-25.el7_3.1, ntp-perl 4.2.6p5-25.el7_3.1 Red Hat Enterprise Linux Workstation (v. 6) ntp 4.2.6p5-10.el6_8.2, ntpdate 4.2.6p5-10.el6_8.2 Red Hat Enterprise Linux Workstation (v. 7) ntp 4.2.6p5-25.el7_3.1, ntpdate 4.2.6p5-25.el7_3.1 Red Hat Enterprise Linux Workstation Optional (v. 6) ntp-perl 4.2.6p5-10.el6_8.2 Red Hat Enterprise Linux Workstation Optional (v. 7) sntp 4.2.6p5-25.el7_3.1, ntp-perl 4.2.6p5-25.el7_3.1
    fixed: vendor fix “If you choose to use restrict default limited ..., be sure to use restrict source ... (without limited) to avoid this attack.” RHSA-2017:0252

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

12.37% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.