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CVE-2017-6463

19
FAUCET Score

CVE-2017-6463 is a denial-of-service vulnerability affecting NTP versions prior to 4.2.8p10 and 4.3.x before 4.3.94. An authenticated remote attacker can crash the NTP daemon by providing an invalid setting within a :config directive, specifically related to the unpeer option. This medium-severity vulnerability has a CVSS score of 6.5, indicating a network-based attack with low complexity and requiring low privileges, leading to high availability impact. There is no evidence of active exploitation, nor are public exploits available in Metasploit or ExploitDB. Despite limited community discussion, it has received some media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
4.2.8CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.2.8:p9:*:*:*:*:*:*
4.3.0CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.3.0:*:*:*:*:*:*:*
4.3.1CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.3.1:*:*:*:*:*:*:*
4.3.2CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.3.2:*:*:*:*:*:*:*
4.3.3CPE matchmatch criteria
cpe:2.3:a:ntp:ntp:4.3.3:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

6.5MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
5.24%
Probability of exploitation in next 30 days
EPSS Percentile
91.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0524 is in the 98th percentile among its peer group of 21,958 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: ntp-0:4.2.6p5-12.el6_9.1
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: ntp-0:4.2.6p5-28.el7
View patch
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: ntp

Vendor Advisories (1)

redhatCVE-2017-6463Moderate

ntp: Authenticated DoS via Malicious Config Option

Mar 21, 2017

References

access.redhat.com / errata/RHSA-2017:3071
access.redhat.com / errata/RHSA-2018:0855
security.freebsd.org / advisories/FreeBSD-SA-17:03.ntp.asc
support.apple.com / HT208144
support.hpe.com / hpsc/doc/public/display
support.ntp.org / bin/view/Main/NtpBug3387
Vendor Advisory
support.ntp.org / bin/view/Main/SecurityNotice
Vendor Advisory
usn.ubuntu.com / 3707-2
securityfocus.com / bid/97049
Third Party AdvisoryVDB Entry
securitytracker.com / id/1038123
Third Party AdvisoryVDB Entry