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CVE-2018-8956

21
FAUCET Score

CVE-2018-8956 describes a denial-of-service vulnerability in ntpd versions 4.2.8p10 through 4.2.8p13, allowing remote attackers to disrupt time synchronization for broadcast NTP clients. An attacker on the same broadcast network can send spoofed mode 3 and mode 5 packets to prevent clients from synchronizing with a broadcast NTP server. Rated as Medium severity (CVSS 5.3), this vulnerability has a low impact (availability loss) and does not require authentication. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
4.2.8CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.2.8:p10:*:*:*:*:*:*
4.2.8CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.2.8:p11:*:*:*:*:*:*
4.2.8CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.2.8:p12:*:*:*:*:*:*
4.2.8CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.2.8:p13:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.04%
Probability of exploitation in next 30 days
EPSS Percentile
86.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0304 is in the 81st percentile among its peer group of 23,725 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Advisories (1)

redhatCVE-2018-8956Moderate

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

May 6, 2020

References

lists.opensuse.org / opensuse-security-announce/2020-07/msg00005.html
lists.opensuse.org / opensuse-security-announce/2020-07/msg00044.html
arxiv.org / abs/2005.01783
Third Party Advisory
nikhiltripathi.in / NTP_attack.pdf
Third Party Advisory
security.netapp.com / advisory/ntap-20200518-0006
tools.ietf.org / html/rfc5905
Third Party Advisory
ntp.org
Vendor Advisory