ntp: crypto-NAK DoS (incorrect fix for CVE-2016-1547)
Published Jul 5, 2016
7.5
HIGHCVSS 3.1
EPSS 44.94%
Description
ntpd in NTP before 4.2.8p8 allows remote attackers to cause a denial of service (daemon crash) via a crypto-NAK packet. NOTE: this vulnerability exists because of an incorrect fix for CVE-2016-1547.
Affected products
No data.
Configuration 3
- 2.1
- 5
- 2.1
- 42.1
- 13.2
- 12
- 11
- 11
- 11
- 12
No data.
Red Hat Enterprise Linux 5
ntp
Not affected
Red Hat Enterprise Linux 6
ntp
Not affected
Red Hat Enterprise Linux 7
ntp
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 5 | ntp | Not affected | n/a |
| Red Hat Enterprise Linux 6 | ntp | Not affected | n/a |
| Red Hat Enterprise Linux 7 | ntp | Not affected | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
This issue did not affect the versions of ntp as shipped with any Red Hat Enterprise Linux version as they did not include the same upstream fix for CVE-2016-1547 that introduced the issue. The fix developed by Red Hat for CVE-2016-1547 did not include this issue.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
No CVSS v3.0 score for this CVE.
AV:N/AC:L/Au:N/C:N/I:N/A:P
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (22 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 44.94% (0.44936) | 98.74th | v5 (v2026.06.15) |
| Jun 15, 2026 | 44.94% (0.44936) | 98.61th | v5 (v2026.06.15) |
| Jun 3, 2026 | 53.72% (0.53716) | 98.04th | v4 (v2025.03.14) |
| Mar 7, 2026 | 59.07% (0.59072) | 98.19th | v4 (v2025.03.14) |
| Dec 28, 2025 | 53.72% (0.53716) | 97.88th | v4 (v2025.03.14) |
| Dec 27, 2025 | 57.88% (0.57878) | 98.09th | v4 (v2025.03.14) |
| Dec 20, 2025 | 53.72% (0.53716) | 97.88th | v4 (v2025.03.14) |
| Dec 13, 2025 | 51.62% (0.51615) | 97.77th | v4 (v2025.03.14) |
| Aug 10, 2025 | 57.88% (0.57878) | 98.07th | v4 (v2025.03.14) |
| Mar 17, 2025 | 62.95% (0.62950) | 98.22th | v4 (v2025.03.14) |
| Dec 17, 2024 | 56.31% (0.56312) | 97.81th | v3 (v2023.03.01) |
| Sep 2, 2024 | 91.18% (0.91182) | 98.94th | v3 (v2023.03.01) |
| Apr 27, 2024 | 92.31% (0.92305) | 98.93th | v3 (v2023.03.01) |
| Feb 21, 2024 | 92.98% (0.92979) | 98.96th | v3 (v2023.03.01) |
| Oct 5, 2023 | 93.69% (0.93695) | 98.82th | v3 (v2023.03.01) |
| Jul 17, 2023 | 94.23% (0.94235) | 98.80th | v3 (v2023.03.01) |
| Jun 7, 2023 | 94.62% (0.94623) | 98.83th | v3 (v2023.03.01) |
| Apr 25, 2023 | 95.17% (0.95175) | 98.91th | v3 (v2023.03.01) |
| Mar 7, 2023 | 95.86% (0.95858) | 99.03th | v3 (v2023.03.01) |
| Mar 6, 2023 | 3.78% (0.03779) | 85.48th | v2 (v2022.01.01) |
| Apr 1, 2022 | 3.78% (0.03779) | 84.01th | v2 (v2022.01.01) |
| Feb 4, 2022 | 3.78% (0.03779) | 67.21th | v2 (v2022.01.01) |
References (18)
- http://bugs.ntp.org/3046 x_refsource_CONFIRMIssue TrackingVendor Advisory
- http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00018.html vendor-advisoryx_refsource_SUSEMailing ListThird Party Advisory
- http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00023.html vendor-advisoryx_refsource_SUSEMailing ListThird Party Advisory
- http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00024.html vendor-advisoryx_refsource_SUSEMailing ListThird Party Advisory
- http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00028.html vendor-advisoryx_refsource_SUSEMailing ListThird Party Advisory
- http://lists.opensuse.org/opensuse-security-announce/2016-06/msg00040.html vendor-advisoryx_refsource_SUSEMailing ListThird Party Advisory
- http://support.ntp.org/bin/view/Main/NtpBug3046 x_refsource_CONFIRMPatchVendor Advisory
- http://support.ntp.org/bin/view/Main/SecurityNotice x_refsource_CONFIRMRelease NotesVendor Advisory
- http://support.ntp.org/bin/view/Main/SecurityNotice#June_2016_ntp_4_2_8p8_NTP_Securi
- http://www.kb.cert.org/vuls/id/321640 third-party-advisoryx_refsource_CERT-VNThird Party AdvisoryUS Government Resource
- http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html x_refsource_CONFIRMThird Party Advisory
- http://www.securitytracker.com/id/1036037 vdb-entryx_refsource_SECTRACKThird Party AdvisoryVDB Entry
- https://access.redhat.com/security/cve/CVE-2016-4957 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1340850 Issue Tracking
- https://nvd.nist.gov/vuln/detail/CVE-2016-4957
- https://security.FreeBSD.org/advisories/FreeBSD-SA-16:24.ntp.asc vendor-advisoryx_refsource_FREEBSDThird Party Advisory
- https://security.gentoo.org/glsa/201607-15 vendor-advisoryx_refsource_GENTOOThird Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2016-4957
Change history (0)
No recorded changes yet.