CVE-2018-7170

CVE-2018-7170 is a medium-severity vulnerability in Ntp with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

• Severity: Medium (CVSS 3.x base score 5.3)
• CVSS v2: 3.5
• EPSS exploit prediction: 3% (84th percentile)
• Actively exploited: Not listed in CISA KEV
• Affected product: Ntp
• Published: 2018-03-06
• Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.

How severe is CVE-2018-7170?

CVE-2018-7170 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2018-7170 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-7170?

CVE-2018-7170 primarily affects Ntp. In total, 29 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-7170?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2018-7170 published?

CVE-2018-7170 was published on 2018-03-06 and last updated on 2026-06-17.

References

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

Affected products (29)

• cpe:2.3:a:ntp:ntp:*:*:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:-:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p1:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p1-beta1:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p1-beta2:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p1-beta3:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p1-beta4:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p1-beta5:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p1-rc1:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p1-rc2:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p2:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p2-rc1:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p2-rc2:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p2-rc3:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p3:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p3-rc1:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p3-rc2:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p3-rc3:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p4:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p5:*:*:*:*:*:*
• cpe:2.3:a:ntp:ntp:4.2.8:p6:*:*:*:*:*:*
• cpe:2.3:a:synology:router_manager:*:*:*:*:*:*:*:*
• cpe:2.3:a:synology:skynas:*:*:*:*:*:*:*:*
• cpe:2.3:a:synology:virtual_diskstation_manager:*:*:*:*:*:*:*:*
• cpe:2.3:o:synology:diskstation_manager:*:*:*:*:*:*:*:*
• cpe:2.3:o:synology:vs960hd_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:a:netapp:hci:-:*:*:*:*:*:*:*
• cpe:2.3:a:netapp:solidfire:-:*:*:*:*:*:*:*
• cpe:2.3:a:hpe:hpux-ntp:*:*:*:*:*:*:*:*

More vulnerabilities in Ntp

• CVE-2018-12327 — Critical (CVSS 9.8): Stack-based buffer overflow in ntpq and ntpdc of NTP version 4.2.8p11 allows an attacker to achieve code execution or…
• CVE-2018-7183 — Critical (CVSS 9.8): Buffer overflow in the decodearr function in ntpq in ntp 4.2.8p6 through 4.2.8p10 allows remote attackers to execute…
• CVE-2015-7871 — Critical (CVSS 9.8): 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…
• CVE-2015-7853 — Critical (CVSS 9.8): The 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…
• CVE-2015-7705 — Critical (CVSS 9.8): The 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…
• CVE-2015-7854 — High (CVSS 8.8): Buffer overflow in the password management functionality in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows…

All CVEs affecting Ntp →

Threat intelligence

Threat-intel indicators referencing this CVE:

• 197.248.207.139 (ipv4-addr)
• 135.129.128.247 (ipv4-addr)
• 119.201.59.224 (ipv4-addr)
• 42.200.60.186 (ipv4-addr)
• 223.197.153.135 (ipv4-addr)
• 125.212.244.35 (ipv4-addr)
• 202.29.220.126 (ipv4-addr)
• 93.42.227.251 (ipv4-addr)