ntp: ephemeral association time spoofing
Published Jan 6, 2017
6.5
MEDIUMCVSS 3.0
EPSS 3.15%
Description
A malicious authenticated peer can create arbitrarily-many ephemeral associations in order to win the clock selection algorithm in ntpd in NTP 4.2.8p4 and earlier and NTPsec 3e160db8dc248a0bcb053b56a80167dc742d2b74 and a5fb34b9cc89b92a8fef2f459004865c93bb7f92 and modify a victim's clock.
Affected products
-
- Version 4.2.8p3StatusaffectedConstraints-
- Version 4.2.8p4StatusaffectedConstraints-
- Version
-
- Version StatusaffectedConstraints-
- 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 5
ntp
Will not fix
Red Hat Enterprise Linux 6
ntp
Will not fix
Red Hat Enterprise Linux 7
ntp
Will not fix
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 5 | ntp | Will not fix | n/a |
| Red Hat Enterprise Linux 6 | ntp | Will not fix | n/a |
| Red Hat Enterprise Linux 7 | ntp | Will not fix | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
Red Hat Product Security has rated this issue as having Low security impact: to exploit this issue, an attacker must have access to a trustedkey if one is configured in the /etc/ntp.key file. This issue is not currently planned to be addressed in future updates. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.
Red Hat mitigation
Assure only trusted hosts have access to the trustedkey.
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:L/UI:N/S:U/C:N/I:H/A:N
AV:N/AC:L/Au:S/C:N/I:P/A:N
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 (13 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 3.15% (0.03147) | 87.48th | v5 (v2026.06.15) |
| Jun 15, 2026 | 3.12% (0.03121) | 86.11th | v5 (v2026.06.15) |
| Mar 30, 2025 | 0.73% (0.00729) | 70.34th | v4 (v2025.03.14) |
| Mar 29, 2025 | 1.97% (0.01970) | 72.66th | v4 (v2025.03.14) |
| Mar 17, 2025 | 0.73% (0.00729) | 70.97th | v4 (v2025.03.14) |
| Dec 12, 2024 | 0.19% (0.00186) | 57.18th | v3 (v2023.03.01) |
| Jun 18, 2024 | 0.19% (0.00186) | 55.96th | v3 (v2023.03.01) |
| Jun 13, 2024 | 0.13% (0.00131) | 48.24th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.13% (0.00131) | 46.22th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.28% (0.01282) | 68.34th | v2 (v2022.01.01) |
| Feb 22, 2023 | 1.28% (0.01282) | 68.05th | v2 (v2022.01.01) |
| Apr 1, 2022 | 1.28% (0.01282) | 65.91th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.28% (0.01282) | 41.72th | v2 (v2022.01.01) |
References (15)
- http://support.ntp.org/bin/view/Main/SecurityNotice#April_2016_NTP_4_2_8p7_Security
- http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html x_refsource_CONFIRM
- http://www.securityfocus.com/bid/88200 vdb-entryx_refsource_BID
- http://www.securitytracker.com/id/1035705 vdb-entryx_refsource_SECTRACK
- http://www.talosintel.com/reports/TALOS-2016-0083/
- http://www.talosintelligence.com/reports/TALOS-2016-0083/ x_refsource_MISCMitigationTechnical DescriptionThird Party Advisory
- https://access.redhat.com/security/cve/CVE-2016-1549 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1331463 Issue Tracking
- https://nvd.nist.gov/vuln/detail/CVE-2016-1549
- 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://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03962en_us x_refsource_CONFIRM
- https://www.cve.org/CVERecord?id=CVE-2016-1549
- https://www.synology.com/support/security/Synology_SA_18_13 x_refsource_CONFIRM
Change history (0)
No recorded changes yet.