CVE-2015-7871

CVE-2015-7871 is a critical-severity vulnerability in Ntp with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 82% places it in the 100th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-287.

Key facts

Description

Crypto-NAK packets in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to bypass authentication.

Frequently asked questions

What is CVE-2015-7871?
Crypto-NAK packets in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to bypass authentication.
How severe is CVE-2015-7871?
CVE-2015-7871 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2015-7871 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 82% (100th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2015-7871?
CVE-2015-7871 primarily affects Ntp. In total, 90 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2015-7871?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2015-7871 published?
CVE-2015-7871 was published on 2017-08-07 and last updated on 2026-06-17.

References

Affected products (90)

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Threat intelligence

Threat-intel indicators referencing this CVE: