HOMEVULNERABILITIESCVE-2018-8956
MEDIUM

CVE-2018-8956

CWE-20Published: May 6, 2020· Updated: Jun 17, 2026

5.3
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2018-8956 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityLow
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected Vendors & Products

ntp1 product(s)
ntp
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttp://www.ntp.org/
ADVISORYhttps://arxiv.org/abs/2005.01783
ADVISORYhttps://nikhiltripathi.in/NTP_attack.pdf
ADVISORYhttps://tools.ietf.org/html/rfc5905
ADVISORYhttp://www.ntp.org/
ADVISORYhttps://arxiv.org/abs/2005.01783
ADVISORYhttps://nikhiltripathi.in/NTP_attack.pdf
ADVISORYhttps://tools.ietf.org/html/rfc5905

All References (14)

→
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

Quick Facts

CVE IDCVE-2018-8956
CVSS Score5.3 / 10
SeverityMEDIUM
WeaknessCWE-20
CISA KEVNo
Affected1 vendor(s)
PublishedMay 6, 2020

Related CVEs (CWE-20)

CVE-2002-1874
10.0
CVE-2002-2365
10.0
CVE-2025-23202
10.0
CVE-2026-47928
10.0
CVE-2002-2236
10.0
CVE-2003-1487
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2018-8956 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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