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Fencer Intel
high 7.5

CVE-2016-4953 in the critical feed json

ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (ephemeral-association demobilization) by sending a spo…

published 2016-07-05 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-5927

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
17.2%
EPSS 17.2% chance of exploitation in 30 days, percentile 97%
public exploits
0
none known

Summary

ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (ephemeral-association demobilization) by sending a spoofed crypto-NAK packet with incorrect authentication data at a certain time.

Patch / fix

  • ntp ntp 4.2.8, 4.3.93
  • ntp Debian 11 1:4.2.8p8+dfsg-1

debian advisories DEBIAN-CVE-2016-4953

  • ntp SLES 11 SP3-TERADATA, SLES 11 SP3-LTSS, SLES 11 SP2-LTSS +3 more 4.2.8p8-47.3
  • ntp SLES 12 SP1, SLES 11 SP4, SLED 12 SP1 +2 more 4.2.8p8-14.1
  • ntp SLES for SAP 12, SLES 12, SLED 12 4.2.8p8-46.8.1

suse advisories SUSE-SU-2016:1602-1SUSE-SU-2016:1584-1SUSE-SU-2016:1568-1SUSE-SU-2016:1563-1

  • ntp openSUSE Tumbleweed 4.2.8p9-1.1

opensuse advisories openSUSE-SU-2024:10181-1

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-2016-4953 updated cvss 2.6

ntp: bad authentication demobilizes ephemeral associations

  • Red Hat Enterprise Linux 5 ntp Red Hat Enterprise Linux 6 ntp, ntpdate, ntp-perl Red Hat Enterprise Linux 7 ntp, sntp, ntpdate, ntp-perl
    not affected: vulnerable code not present

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

cisa ICSA-21-103-11 updated cvss 7.5

Siemens TIM 4R-IE Devices

  • Siemens SIPLUS NET TIM 4R-IE (6AG1800-4BA00-7AA0) Siemens SIPLUS NET TIM 4R-IE DNP3 (6AG1803-4BA00-7AA0) Siemens TIM 4R-IE (6NH7800-4BA00) Siemens TIM 4R-IE DNP3 (6NH7803-4BA00-0AA0)
    affected: workaround, no fix planned

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

cisa ICSA-21-159-11 updated cvss 7.5

Siemens SIMATIC NET CP 443-1 OPC UA

  • Siemens SIMATIC CP 443-1 OPC UA
    affected: mitigation, no fix planned

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

17.24% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-09).

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 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness

References

Sources

Fencer Intel 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.