What’s Vulnerable › Vulnerabilities

CVE-2015-7871

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 81.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2017-08-07 · updated 2026-06-17
• Weakness: CWE-287

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.

Affected products

• Debian Linux: 7.0, 8.0, 9.0
• Clustered Data ONTAP: all versions
• NetApp Data ONTAP operating in 7-Mode: all versions
• NetApp Oncommand Balance: all versions
• NetApp Oncommand Performance Manager: all versions
• NetApp OnCommand Unified Manager for 7-Mode (core package): all versions
• NTP: from 4.2.6 before 4.2.8; from 4.3.0 before 4.3.77; 4.2.5-p186, 4.2.5-p187, 4.2.5-p188, 4.2.5-p189, 4.2.5-p190, 4.2.5-p191 (+75) — fixed in 4.2.8, 4.3.77

How to fix

Upgrade to a fixed version: NTP 4.2.8, 4.3.77. Check the vendor advisory for mitigations.

References

• http://support.ntp.org/bin/view/Main/NtpBug2941
• http://www.debian.org/security/2015/dsa-3388
• http://www.securityfocus.com/bid/77287
• http://www.securitytracker.com/id/1033951
• https://bugzilla.redhat.com/show_bug.cgi?id=1274265
• https://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf
• https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05270839
• https://security.gentoo.org/glsa/201604-03
• https://security.gentoo.org/glsa/201607-15
• https://security.netapp.com/advisory/ntap-20171004-0001/
• http://support.ntp.org/bin/view/Main/NtpBug2941
• http://www.debian.org/security/2015/dsa-3388

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