CVE-2018-7170

ntpd in ntp 4.2.x before 4.2.8p7 and 4.3.x before 4.3.92 allows authenticated users that know the private symmetric key to create arbitrarily-many ephemeral associations in order to win the clock selection of ntpd and modify a victim's clock via a Sybil attack. This issue exists because of an incomplete fix for CVE-2016-1549.

Published: 2018-03-06 Last update: 2025-01-14 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-7170 is rated Moderate Risk (44.8/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.54%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2018-7170

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-27 0.64% 0.54% -0.10%
2 2026-05-24 0.54% 0.64% +0.10%
3 2026-05-19 — 0.54% —

Full EPSS history (27 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-7170

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 1.6 3.6 [email protected]
3.5 2.0 LOW
AV:N/AC:M/Au:S/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 6.8 2.9 [email protected]

Weakness enumeration for CVE-2018-7170

OS Trackers for CVE-2018-7170

vendor priority summary link
debian unimportant CVE-2018-7170 unimportant priority: Debian including 2 source packages (ntp, ntpsec), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. https://security-tracker.debian.org/tracker/CVE-2018-7170
gentoo normal CVE-2018-7170: 1 GLSA(s) (201805-12), 1 atom(s) (net-misc/ntp); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2018-7170
redhat low — https://access.redhat.com/security/cve/CVE-2018-7170
suse low CVE-2018-7170 severity low: SUSE including 18 source package names (ntp-4.2.8p12-4.3.2, ntp-4.2.8p12-46.29.2, …), 99 product×package rows across 71 product lines (Image SLES12-SP5-Azure-BYOS, Image SLES12-SP5-Azure-Basic-On-Demand, … (71 product lines)): Fixed 99. https://www.suse.com/security/cve/CVE-2018-7170/
ubuntu low CVE-2018-7170 low priority: Ubuntu including 1 source packages (ntp), 20 status rows across 20 suites (artful, bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): released 9, DNE 7, needed 3, ignored 1. https://ubuntu.com/security/CVE-2018-7170

Affected software / configurations for CVE-2018-7170

Vendor Product Version Raw CPE
ntp ntp >= 4.2.0, < 4.2.8 cpe:2.3:a:ntp:ntp:*:*:*:*:*:*:*:*
ntp ntp >= 4.3.0, < 4.3.92 cpe:2.3:a:ntp:ntp:*:*:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:-:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-beta1:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-beta2:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-beta3:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-beta4:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-beta5:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-rc1:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p1-rc2:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p2:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p2-rc1:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p2-rc2:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p2-rc3:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p3:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p3-rc1:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p3-rc2:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p3-rc3:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p4:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p5:*:*:*:*:*:*
ntp ntp 4.2.8 cpe:2.3:a:ntp:ntp:4.2.8:p6:*:*:*:*:*:*
synology router_manager >= 1.1, < 1.1.6-6931-3 cpe:2.3:a:synology:router_manager:*:*:*:*:*:*:*:*
synology skynas < 6.1.5-15254 cpe:2.3:a:synology:skynas:*:*:*:*:*:*:*:*
synology virtual_diskstation_manager < 6.1.6-15266 cpe:2.3:a:synology:virtual_diskstation_manager:*:*:*:*:*:*:*:*
synology diskstation_manager >= 5.2, < 6.1.6-15266 cpe:2.3:o:synology:diskstation_manager:*:*:*:*:*:*:*:*
synology vs960hd_firmware < 2.2.3-1505 cpe:2.3:o:synology:vs960hd_firmware:*:*:*:*:*:*:*:*
netapp hci — cpe:2.3:a:netapp:hci:-:*:*:*:*:*:*:*
netapp solidfire — cpe:2.3:a:netapp:solidfire:-:*:*:*:*:*:*:*
hpe hpux-ntp < c.4.2.8.4.0 cpe:2.3:a:hpe:hpux-ntp:*:*:*:*:*:*:*:*

References for CVE-2018-7170

URL Tags
http://packetstormsecurity.com/files/146631/Slackware-Security-Advisory-ntp-Updates.html Third Party Advisory VDB Entry
http://support.ntp.org/bin/view/Main/NtpBug3415 Third Party Advisory
http://www.securityfocus.com/archive/1/541824/100/0/threaded Third Party Advisory VDB Entry
http://www.securityfocus.com/bid/103194 Third Party Advisory VDB Entry
https://bugzilla.redhat.com/show_bug.cgi?id=1550214 Issue Tracking Third Party Advisory
https://security.FreeBSD.org/advisories/FreeBSD-SA-18:02.ntp.asc Third Party Advisory
https://security.gentoo.org/glsa/201805-12 Third Party Advisory
https://security.netapp.com/advisory/ntap-20180626-0001/ Third Party Advisory
https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03962en_us Third Party Advisory
https://www.synology.com/support/security/Synology_SA_18_13 Third Party Advisory
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