CVE-2018-8956

Name: CVE-2018-8956
Creator: NVD / NIST
Published: 2020-05-06T19:15:12.41+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 3.08%

Last modified Jun 17, 2026

CVE-2018-8956 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. 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.. EPSS estimates a 3.08% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS Probability

3.08%

86.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-20

Affected Software

Vendor	Product	Versions	Update
Ntp	Ntp	4.2.8	P10

References

http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00005.html
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00044.html
http://www.ntp.org/Vendor Advisory
https://arxiv.org/abs/2005.01783Third Party Advisory
https://nikhiltripathi.in/NTP_attack.pdfThird Party Advisory
https://security.netapp.com/advisory/ntap-20200518-0006/
https://tools.ietf.org/html/rfc5905Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00005.html
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00044.html
http://www.ntp.org/Vendor Advisory
https://arxiv.org/abs/2005.01783Third Party Advisory
https://nikhiltripathi.in/NTP_attack.pdfThird Party Advisory
https://security.netapp.com/advisory/ntap-20200518-0006/
https://tools.ietf.org/html/rfc5905Third Party Advisory

Timeline

Published: May 6, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-8956?

How severe is CVE-2018-8956?

CVE-2018-8956 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 3.08% probability of exploitation in the next 30 days.

How do I fix CVE-2018-8956?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2018-8956?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST