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Vulnerability record · CVE-2017-6463 · published 27 March 2017

CVE-2017-6463: Ntp improper input validation vulnerability

Ntp · Ntp

NTP before 4.2.8p10 and 4.3.x before 4.3.94 allows remote authenticated users to cause a denial of service (daemon crash) via an invalid setting in a :config directive, related to the unpeer option.

6.5 CVSS 3.0 Medium EPSS 5.2% · top 7.8% CWE-20 · Improper input validation
6.5CVSS 3.0 base score, v2 4.0
5.2%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
20References
17 Jun 2026Last modified by NVD

Description

NTP before 4.2.8p10 and 4.3.x before 4.3.94 allows remote authenticated users to cause a denial of service (daemon crash) via an invalid setting in a :config directive, related to the unpeer option.

CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://support.ntp.org/bin/view/Main/NtpBug3387 Vendor Advisory
http://support.ntp.org/bin/view/Main/SecurityNotice#March_2017_ntp_4_2_8p10_NTP_Secu Vendor Advisory
http://www.securityfocus.com/bid/97049 Third Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1038123 Third Party AdvisoryVDB Entry
https://access.redhat.com/errata/RHSA-2017:3071
https://access.redhat.com/errata/RHSA-2018:0855
https://security.FreeBSD.org/advisories/FreeBSD-SA-17:03.ntp.asc
https://support.apple.com/HT208144
https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03962en_us
https://usn.ubuntu.com/3707-2/
http://support.ntp.org/bin/view/Main/NtpBug3387 Vendor Advisory
http://support.ntp.org/bin/view/Main/SecurityNotice#March_2017_ntp_4_2_8p10_NTP_Secu Vendor Advisory
http://www.securityfocus.com/bid/97049 Third Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1038123 Third Party AdvisoryVDB Entry
https://access.redhat.com/errata/RHSA-2017:3071
https://access.redhat.com/errata/RHSA-2018:0855
https://security.FreeBSD.org/advisories/FreeBSD-SA-17:03.ntp.asc
https://support.apple.com/HT208144
https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03962en_us
https://usn.ubuntu.com/3707-2/

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2018-12327Ntp out-of-bounds write vulnerabilityStack-based buffer overflow in ntpq and ntpdc of NTP version 4.2.8p11 allows an attacker to achieve code execution or escalate to higher privileges v…EPSS 28%9.8CVE-2018-7183Ntp out-of-bounds write vulnerabilityBuffer overflow in the decodearr function in ntpq in ntp 4.2.8p6 through 4.2.8p10 allows remote attackers to execute arbitrary code by leveraging an …EPSS 10%9.8CVE-2015-7705Ntp improper input validation vulnerabilityThe rate limiting feature in NTP 4.x before 4.2.8p4 and 4.3.x before 4.3.77 allows remote attackers to have unspecified impact via a large number of …EPSS 12%9.8CVE-2015-7853Ntp classic buffer overflow vulnerabilityThe datalen parameter in the refclock driver in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to execute arbitrary code o…EPSS 12%9.8CVE-2015-7871ntpd Crypto-NAK packets bypass authenticationntpd in NTP 4.2.x before 4.2.8p4 and 4.3.x before 4.3.77 mishandles Crypto-NAK packets, allowing remote attackers to bypass authentication. Because N…EPSS 82%analysed8.8CVE-2015-7849Ntp use after free vulnerabilityUse-after-free vulnerability in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote authenticated users to possibly execute arbit…EPSS 17%8.8CVE-2015-7854Ntp classic buffer overflow vulnerabilityBuffer overflow in the password management functionality in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote authenticated users to ca…EPSS 15%8.8CVE-2017-6458Ntp memory buffer overflow vulnerabilityMultiple buffer overflows in the ctl_put* functions in NTP before 4.2.8p10 and 4.3.x before 4.3.94 allow remote authenticated users to have unspecifi…EPSS 6.5%

Source: NIST National Vulnerability Database (record CVE-2017-6463), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.