CVE-2016-4956

CVE-2016-4956 is a medium-severity vulnerability in Ntp with a CVSS 3.x base score of 5.3. Its EPSS exploit-prediction score of 16% places it in the 97th percentile, indicating an elevated likelihood of exploitation.

Key facts

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.

Frequently asked questions

What is CVE-2016-4956?
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.
How severe is CVE-2016-4956?
CVE-2016-4956 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2016-4956 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 16% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-4956?
CVE-2016-4956 primarily affects Ntp. In total, 35 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-4956?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2016-4956 published?
CVE-2016-4956 was published on 2016-07-05 and last updated on 2026-06-17.

References

Affected products (35)

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Threat intelligence

Threat-intel indicators referencing this CVE: