MEDIUM
CVE-2016-4956
NVD-CWE-noinfoPublished: July 5, 2016· Updated: Jun 17, 2026
5.3
CVSS v3.1
Official Description
ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (interleaved-mode transition and time change) via a spoofed broadcast packet. NOTE: this vulnerability exists because of an incomplete fix for CVE-2016-1548.
Technical Analysis
CVE-2016-4956 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
novell1 product(s)
suse manager
ntp1 product(s)
ntp
openSUSE2 product(s)
leapopensuse
Oracle1 product(s)
solaris
siemens2 product(s)
simatic net cp 443-1 opc ua firmwaresimatic net cp 443-1 opc ua
SUSE4 product(s)
manager proxyopenstack cloudlinux enterprise desktoplinux enterprise server
Source: NVD CPE · 14 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
All References (66)
→
http://bugs.ntp.org/3042Issue Tracking · Vendor Advisory
→
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00018.htmlMailing List · Third Party Advisory
→
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00023.htmlMailing List · Third Party Advisory
→
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00024.htmlMailing List · Third Party Advisory
→
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00028.htmlMailing List · Third Party Advisory
→
http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00040.htmlMailing List · Third Party Advisory
→
http://support.ntp.org/bin/view/Main/NtpBug3042Vendor Advisory
→
http://support.ntp.org/bin/view/Main/SecurityNoticeRelease Notes · Vendor Advisory
→
http://www.kb.cert.org/vuls/id/321640Third Party Advisory · US Government Resource
→
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.htmlThird Party Advisory
Quick Facts
CVE IDCVE-2016-4956
CVSS Score5.3 / 10
SeverityMEDIUM
WeaknessNVD-CWE-noinfo
CISA KEVNo
Affected6 vendor(s)
PublishedJul 5, 2016
Related CVEs (NVD-CWE-noinfo)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2016-4956 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.