HIGH
ntp: bad authentication demobilizes ephemeral associations
Published Jul 5, 2016
7.5
HIGHCVSS 3.1
EPSS 17.24%
Description
ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a denial of service (ephemeral-association demobilization) by sending a spoofed crypto-NAK packet with incorrect authentication data at a certain time.
Affected products
No data.
Configuration 1
OR
- ≥ 4.2.0 · < 4.2.8
- ≥ 4.3.0 · < 4.3.93
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
- 4.2.8
Configuration 3
OR
- 2.1
- 2.1
- 5
- 42.1
- 13.2
- 12
- 11
- 11
- 11
- 12
Configuration 4
AND
Running on/with
- n/a
Configuration 5
AND
- n/a
Configuration 6
AND
- n/a
Running on/with
- n/a
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 already included a fix for this issue in the patch provided to fix the CVE-2015-7979 issue. The fix for this issue (developed by Red Hat) was different from the one provided by upstream, and thus ntp versions in RHEL are not affected by CVE-2016-4953.
Metrics
No CVSS v4.0 score for this CVE.
7.5 HIGH NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality Impact None
Integrity Impact None
Availability Impact High
No CVSS v3.0 score for this CVE.
5.0 MEDIUM NVD
AV:N/AC:L/Au:N/C:N/I:N/A:P
Access Vector Network
Access Complexity Low
Authentication None
Confidentiality Impact None
Integrity Impact None
Availability Impact Partial
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
17.24% 0.17245
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
EPSS probability 0.17245
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 (26 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 17.24% (0.17245) | 97.01th | v5 (v2026.06.15) |
| Jun 15, 2026 | 17.24% (0.17245) | 96.70th | v5 (v2026.06.15) |
| Jun 3, 2026 | 12.72% (0.12716) | 94.13th | v4 (v2025.03.14) |
| Dec 28, 2025 | 14.37% (0.14372) | 94.19th | v4 (v2025.03.14) |
| Dec 27, 2025 | 13.35% (0.13354) | 93.98th | v4 (v2025.03.14) |
| Dec 16, 2025 | 14.37% (0.14372) | 94.17th | v4 (v2025.03.14) |
| Aug 24, 2025 | 12.64% (0.12644) | 93.71th | v4 (v2025.03.14) |
| Aug 10, 2025 | 16.60% (0.16604) | 94.63th | v4 (v2025.03.14) |
| Mar 30, 2025 | 19.20% (0.19204) | 94.87th | v4 (v2025.03.14) |
| Mar 29, 2025 | 15.00% (0.15003) | 90.97th | v4 (v2025.03.14) |
| Mar 24, 2025 | 19.20% (0.19204) | 94.85th | v4 (v2025.03.14) |
| Mar 23, 2025 | 20.59% (0.20588) | 94.85th | v4 (v2025.03.14) |
| Mar 19, 2025 | 13.05% (0.13053) | 93.25th | v4 (v2025.03.14) |
| Mar 17, 2025 | 10.79% (0.10786) | 92.80th | v4 (v2025.03.14) |
| Dec 17, 2024 | 15.76% (0.15764) | 95.90th | v3 (v2023.03.01) |
| Dec 12, 2024 | 3.41% (0.03411) | 91.80th | v3 (v2023.03.01) |
| Apr 27, 2024 | 3.25% (0.03253) | 91.14th | v3 (v2023.03.01) |
| Feb 21, 2024 | 2.32% (0.02320) | 89.40th | v3 (v2023.03.01) |
| Oct 5, 2023 | 2.03% (0.02029) | 87.61th | v3 (v2023.03.01) |
| Jul 17, 2023 | 1.67% (0.01674) | 85.96th | v3 (v2023.03.01) |
| Jun 7, 2023 | 1.43% (0.01427) | 84.63th | v3 (v2023.03.01) |
| Apr 25, 2023 | 1.38% (0.01382) | 84.32th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.93% (0.00934) | 80.62th | v3 (v2023.03.01) |
| Mar 6, 2023 | 4.36% (0.04358) | 88.02th | v2 (v2022.01.01) |
| Apr 1, 2022 | 4.36% (0.04358) | 86.83th | v2 (v2022.01.01) |
| Feb 4, 2022 | 4.36% (0.04358) | 70.59th | v2 (v2022.01.01) |
Weaknesses (1)
References (37)
- http://bugs.ntp.org/3045 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/msg00020.html vendor-advisoryx_refsource_SUSE
- 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://lists.opensuse.org/opensuse-security-announce/2016-07/msg00026.html vendor-advisoryx_refsource_SUSE
- http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00042.html vendor-advisoryx_refsource_SUSE
- http://packetstormsecurity.com/files/137321/Slackware-Security-Advisory-ntp-Updates.html x_refsource_MISC
- http://packetstormsecurity.com/files/137322/FreeBSD-Security-Advisory-FreeBSD-SA-16-24.ntp.html x_refsource_MISC
- http://support.ntp.org/bin/view/Main/NtpBug3045 x_refsource_CONFIRMPatchVendor Advisory
- http://support.ntp.org/bin/view/Main/SecurityNotice x_refsource_CONFIRMVendor Advisory
- http://support.ntp.org/bin/view/Main/SecurityNotice#June_2016_ntp_4_2_8p8_NTP_Securi
- http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160603-ntpd vendor-advisoryx_refsource_CISCO
- 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.securityfocus.com/archive/1/538599/100/0/threaded mailing-listx_refsource_BUGTRAQ
- http://www.securityfocus.com/archive/1/538600/100/0/threaded mailing-listx_refsource_BUGTRAQ
- http://www.securityfocus.com/archive/1/540683/100/0/threaded mailing-listx_refsource_BUGTRAQ
- http://www.securityfocus.com/archive/1/archive/1/538599/100/0/threaded mailing-listx_refsource_BUGTRAQ
- http://www.securityfocus.com/archive/1/archive/1/538600/100/0/threaded mailing-listx_refsource_BUGTRAQ
- http://www.securityfocus.com/archive/1/archive/1/540683/100/0/threaded mailing-listx_refsource_BUGTRAQ
- http://www.securityfocus.com/bid/91010 vdb-entryx_refsource_BIDThird Party AdvisoryVDB Entry
- http://www.securitytracker.com/id/1036037 vdb-entryx_refsource_SECTRACKThird Party AdvisoryVDB Entry
- https://access.redhat.com/security/cve/CVE-2016-4953 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1340852 Issue Tracking
- https://cert-portal.siemens.com/productcert/pdf/ssa-211752.pdf x_refsource_CONFIRMThird Party Advisory
- https://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf x_refsource_CONFIRMThird Party Advisory
- https://h20566.www2.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf03757en_us x_refsource_CONFIRMThird Party Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2016-4953
- 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://us-cert.cisa.gov/ics/advisories/icsa-21-103-11 x_refsource_CONFIRMThird Party AdvisoryUS Government Resource
- https://us-cert.cisa.gov/ics/advisories/icsa-21-159-11 x_refsource_MISC
- https://www.cve.org/CVERecord?id=CVE-2016-4953
- https://www.kb.cert.org/vuls/id/321640 third-party-advisoryx_refsource_CERT-VN
Change history (0)
No recorded changes yet.
Sources
CVE.org / MITRE
Status PUBLISHED
Assigner mitre
Published Jul 5, 2016
Updated Aug 6, 2024
Reserved May 23, 2016
Link CVE-2016-4953
CISA Vulnrichment
Updated n/a