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Fencer Intel
medium 5.3

CVE-2018-8956 json

ntpd in ntp 4.2.8p10, 4.2.8p11, 4.2.8p12 and 4.2.8p13 allow remote attackers to prevent a broadcast client from synchronizing its clock wit…

published 6y ago modified 4mo ago also EUVD-2018-20563

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.1%
EPSS 3.1% chance of exploitation in 30 days, percentile 88%
public exploits
0
none known

Summary

ntpd in ntp 4.2.8p10, 4.2.8p11, 4.2.8p12 and 4.2.8p13 allow remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via soofed mode 3 and mode 5 packets. The attacker must either be a part of the same broadcast network or control a slave in that broadcast network that can capture certain required packets on the attacker's behalf and send them to the attacker.

Patch / fix

  • ntp Debian 11 1:4.2.8p14+dfsg-1

debian advisories DEBIAN-CVE-2018-8956

  • ntp SLES for SAP 15, SLES 15-LTSS, SLE Module for Legacy 15 SP2 +1 more 4.2.8p15-4.10.1
  • ntp SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +12 more 4.2.8p15-88.1
  • ntp SLES 11 SP4-LTSS 4.2.8p15-64.16.1

suse advisories SUSE-SU-2020:1823-1SUSE-SU-2020:14415-1SUSE-SU-2020:1805-1

  • ntp openSUSE Tumbleweed 4.2.8p15-7.2
  • ntp openSUSE Leap 15.2 4.2.8p15-lp152.3.3.1
  • ntp openSUSE Leap 15.1 4.2.8p15-lp151.2.3.1

opensuse advisories openSUSE-SU-2024:11102-1openSUSE-SU-2020:1007-1openSUSE-SU-2020:0934-1

  • ntp Arch Linux 4.2.8.p14-1

arch linux advisories AVG-1151

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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-2018-8956 updated cvss 5.3

ntp: ntpd allows remote attackers to prevent a broadcast client from synchronizing its clock

  • 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

Exploit prediction

3.14% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness
  • CWE-20 Improper Input Validation

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.