ntp: crypto-NAK preemptable association denial of service
Published Jan 6, 2017
5.3
MEDIUMCVSS 3.0
EPSS 5.11%
Description
An off-path attacker can cause a preemptible client association to be demobilized in NTP 4.2.8p4 and earlier and NTPSec a5fb34b9cc89b92a8fef2f459004865c93bb7f92 by sending a crypto NAK packet to a victim client with a spoofed source address of an existing associated peer. This is true even if authentication is enabled.
Affected products
-
- Version 4.2.8p3StatusaffectedConstraints-
- Version 4.2.8p4StatusaffectedConstraints-
- Version
-
- Version StatusaffectedConstraints-
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NTP Project | NTP | n/a |
| |||||||||
| NTPsec Project | NTPSec | n/a |
|
No data.
Red Hat Enterprise Linux 6
ntp-0:4.2.6p5-10.el6.1
Fixed · RHSA-2016:1141
Red Hat Enterprise Linux 6.7 Extended Update Support
ntp-0:4.2.6p5-5.el6_7.5
Fixed · RHSA-2016:1552
Red Hat Enterprise Linux 7
ntp-0:4.2.6p5-22.el7_2.2
Fixed · RHSA-2016:1141
Red Hat Enterprise Linux 5
ntp
Will not fix
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 6 | ntp-0:4.2.6p5-10.el6.1 | Fixed | RHSA-2016:1141 |
| Red Hat Enterprise Linux 6.7 Extended Update Support | ntp-0:4.2.6p5-5.el6_7.5 | Fixed | RHSA-2016:1552 |
| Red Hat Enterprise Linux 7 | ntp-0:4.2.6p5-22.el7_2.2 | Fixed | RHSA-2016:1141 |
| Red Hat Enterprise Linux 5 | ntp | Will not fix | n/a |
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
No CVSS v3.1 score for this CVE.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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 (12 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 5.11% (0.05110) | 92.11th | v5 (v2026.06.15) |
| Jun 15, 2026 | 5.11% (0.05110) | 91.26th | v5 (v2026.06.15) |
| Jan 14, 2026 | 3.66% (0.03664) | 87.53th | v4 (v2025.03.14) |
| Mar 17, 2025 | 1.85% (0.01846) | 81.81th | v4 (v2025.03.14) |
| Dec 12, 2024 | 0.84% (0.00840) | 82.80th | v3 (v2023.03.01) |
| Jun 18, 2024 | 0.84% (0.00840) | 82.19th | v3 (v2023.03.01) |
| Feb 29, 2024 | 0.59% (0.00593) | 77.77th | v3 (v2023.03.01) |
| Feb 8, 2024 | 0.53% (0.00525) | 76.25th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.53% (0.00525) | 73.36th | v3 (v2023.03.01) |
| Mar 6, 2023 | 2.69% (0.02686) | 82.85th | v2 (v2022.01.01) |
| Apr 1, 2022 | 2.69% (0.02686) | 81.17th | v2 (v2022.01.01) |
| Feb 4, 2022 | 2.69% (0.02686) | 62.66th | v2 (v2022.01.01) |
References (21)
- http://rhn.redhat.com/errata/RHSA-2016-1552.html vendor-advisoryx_refsource_REDHAT
- http://support.ntp.org/bin/view/Main/SecurityNotice#April_2016_NTP_4_2_8p7_Security
- http://www.debian.org/security/2016/dsa-3629 vendor-advisoryx_refsource_DEBIAN
- http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html x_refsource_CONFIRM
- http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html x_refsource_CONFIRM
- http://www.securityfocus.com/bid/88276 vdb-entryx_refsource_BID
- http://www.securitytracker.com/id/1035705 vdb-entryx_refsource_SECTRACK
- http://www.talosintel.com/reports/TALOS-2016-0081/
- http://www.talosintelligence.com/reports/TALOS-2016-0081/ x_refsource_MISCMitigationTechnical DescriptionThird Party Advisory
- https://access.redhat.com/errata/RHSA-2016:1141 vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2016-1547 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1331461 Issue Tracking
- https://cert-portal.siemens.com/productcert/pdf/ssa-211752.pdf x_refsource_CONFIRM
- https://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf x_refsource_CONFIRM
- https://nvd.nist.gov/vuln/detail/CVE-2016-1547
- https://security.FreeBSD.org/advisories/FreeBSD-SA-16:16.ntp.asc vendor-advisoryx_refsource_FREEBSD
- https://security.gentoo.org/glsa/201607-15 vendor-advisoryx_refsource_GENTOO
- https://security.netapp.com/advisory/ntap-20171004-0002/ x_refsource_CONFIRM
- https://us-cert.cisa.gov/ics/advisories/icsa-21-103-11 x_refsource_CONFIRM
- https://www.arista.com/en/support/advisories-notices/security-advisories/1332-security-advisory-19 x_refsource_MISC
- https://www.cve.org/CVERecord?id=CVE-2016-1547
Change history (0)
No recorded changes yet.