CVE-2018-8956
ntpd in ntp 4.2.8p10, 4.2.8p11, 4.2.8p12 and 4.2.8p13 allow remote attackers to prevent a...
ntpd in ntp 4.2.8p10, 4.2.8p11, 4.2.8p12 and 4.2.8p13 allow remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via soofed mode 3 and mode 5 packets. The attacker must either be a part of the same broadcast network or control a slave in that broadcast network that can capture certain required packets on the attacker's behalf and send them to the attacker.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Exploit likelihood
What each source reports
NVD Score used
ntpd in ntp 4.2.8p10, 4.2.8p11, 4.2.8p12 and 4.2.8p13 allow remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via soofed mode 3 and mode 5 packets. The attacker must either be a part of the same broadcast network or control a slave in that broadcast network that can capture certain required packets on the attacker's behalf and send them to the attacker.
- Record
CVE-2018-8956- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:N/A:P - Weakness
- CWE-20
- Updated
- 2026-11-02
CVE List No score
ntpd in ntp 4.2.8p10, 4.2.8p11, 4.2.8p12 and 4.2.8p13 allow remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via soofed mode 3 and mode 5 packets. The attacker must either be a part of the same broadcast network or control a slave in that broadcast network that can capture certain required packets on the attacker's behalf and send them to the attacker.
- Record
CVE-2018-8956- Updated
- 2026-11-02
EUVDEUVD-2018-20563 No score
ntpd in ntp 4.2.8p10, 4.2.8p11, 4.2.8p12 and 4.2.8p13 allow remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via soofed mode 3 and mode 5 packets. The attacker must either be a part of the same broadcast network or control a slave in that broadcast network that can capture certain required packets on the attacker's behalf and send them to the attacker.
- Record
EUVD-2018-20563- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-gg7p-jc5w-p68m No score
ntpd in ntp 4.2.8p10, 4.2.8p11, 4.2.8p12 and 4.2.8p13 allow remote attackers to prevent a...
ntpd in ntp 4.2.8p10, 4.2.8p11, 4.2.8p12 and 4.2.8p13 allow remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via soofed mode 3 and mode 5 packets. The attacker must either be a part of the same broadcast network or control a slave in that broadcast network that can capture certain required packets on the attacker's behalf and send them to the attacker.
- Record
GHSA-gg7p-jc5w-p68m- Updated
- 2026-11-02
OSV
ntpd in ntp 4.2.8p10, 4.2.8p11, 4.2.8p12 and 4.2.8p13 allow remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via soofed mode 3 and mode 5 packets. The attacker must either be a part of the same broadcast network or control a slave in that broadcast network that can capture certain required packets on the attacker's behalf and send them to the attacker.
- Record
CVE-2018-8956- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Updated
- 2026-11-02
OSVDEBIAN-CVE-2018-8956
ntpd in ntp 4.2.8p10, 4.2.8p11, 4.2.8p12 and 4.2.8p13 allow remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via soofed mode 3 and mode 5 packets. The attacker must either be a part of the same broadcast network or control a slave in that broadcast network that can capture certain required packets on the attacker's behalf and send them to the attacker.
- Record
DEBIAN-CVE-2018-8956- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Updated
- 2026-11-02
Show 7 moreShow less
OSVUBUNTU-CVE-2018-8956
ntpd in ntp 4.2.8p10, 4.2.8p11, 4.2.8p12 and 4.2.8p13 allow remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via soofed mode 3 and mode 5 packets. The attacker must either be a part of the same broadcast network or control a slave in that broadcast network that can capture certain required packets on the attacker's behalf and send them to the attacker.
- Record
UBUNTU-CVE-2018-8956- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Updated
- 2026-11-02
OSVopenSUSE-SU-2020:0934-1 No score
Security update for ntp
This update for ntp fixes the following issues:
ntp was updated to 4.2.8p15
- CVE-2020-11868: Fixed an issue which a server mode packet with spoofed source address frequently send to the client ntpd could have caused denial of service (bsc#1169740).
- CVE-2018-8956: Fixed an issue which could have allowed remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via spoofed mode 3 and mode 5 packets (bsc#1171355).
- CVE-2020-13817: Fixed an issue which an off-path attacker with the ability to query time from victim's ntpd instance could have modified the victim's clock by a limited amount (bsc#1172651).
- CVE-2020-15025: Fixed an issue which remote attacker could have caused denial of service by consuming the memory when a CMAC key was used andassociated with a CMAC algorithm in the ntp.keys (bsc#1173334).
- Removed an OpenSSL version warning (bsc#992038 and bsc#1125401).
This update was imported from the SUSE:SLE-15:Update update project.
- Record
openSUSE-SU-2020:0934-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2020:1007-1 No score
Security update for ntp
This update for ntp fixes the following issues:
ntp was updated to 4.2.8p15
- CVE-2020-11868: Fixed an issue which a server mode packet with spoofed source address frequently send to the client ntpd could have caused denial of service (bsc#1169740).
- CVE-2018-8956: Fixed an issue which could have allowed remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via spoofed mode 3 and mode 5 packets (bsc#1171355).
- CVE-2020-13817: Fixed an issue which an off-path attacker with the ability to query time from victim's ntpd instance could have modified the victim's clock by a limited amount (bsc#1172651).
- CVE-2020-15025: Fixed an issue which remote attacker could have caused denial of service by consuming the memory when a CMAC key was used andassociated with a CMAC algorithm in the ntp.keys (bsc#1173334).
- Removed an OpenSSL version warning (bsc#992038 and bsc#1125401).
This update was imported from the SUSE:SLE-15:Update update project.
- Record
openSUSE-SU-2020:1007-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2024:11102-1 No score
ntp-4.2.8p15-7.2 on GA media
These are all security issues fixed in the ntp-4.2.8p15-7.2 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2024:11102-1- Updated
- 2026-11-02
OSVSUSE-SU-2020:14415-1 No score
Security update for ntp
This update for ntp fixes the following issues:
ntp was updated to 4.2.8p15
- CVE-2020-11868: Fixed an issue which a server mode packet with spoofed source address frequently send to the client ntpd could have caused denial of service (bsc#1169740).
- CVE-2018-8956: Fixed an issue which could have allowed remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via spoofed mode 3 and mode 5 packets (bsc#1171355).
- CVE-2020-13817: Fixed an issue which an off-path attacker with the ability to query time from victim's ntpd instance could have modified the victim's clock by a limited amount (bsc#1172651).
- CVE-2020-15025: Fixed an issue which remote attacker could have caused denial of service by consuming the memory when a CMAC key was used andassociated with a CMAC algorithm in the ntp.keys (bsc#1173334).
- Record
SUSE-SU-2020:14415-1- Updated
- 2026-11-02
OSVSUSE-SU-2020:1805-1 No score
Security update for ntp
This update for ntp fixes the following issues:
ntp was updated to 4.2.8p15
- CVE-2020-11868: Fixed an issue which a server mode packet with spoofed source address frequently send to the client ntpd could have caused denial of service (bsc#1169740).
- CVE-2018-8956: Fixed an issue which could have allowed remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via spoofed mode 3 and mode 5 packets (bsc#1171355).
- CVE-2020-13817: Fixed an issue which an off-path attacker with the ability to query time from victim's ntpd instance could have modified the victim's clock by a limited amount (bsc#1172651).
- CVE-2020-15025: Fixed an issue which remote attacker could have caused denial of service by consuming the memory when a CMAC key was used andassociated with a CMAC algorithm in the ntp.keys (bsc#1173334).
- Record
SUSE-SU-2020:1805-1- Updated
- 2026-11-02
OSVSUSE-SU-2020:1823-1 No score
Security update for ntp
This update for ntp fixes the following issues:
ntp was updated to 4.2.8p15
- CVE-2020-11868: Fixed an issue which a server mode packet with spoofed source address frequently send to the client ntpd could have caused denial of service (bsc#1169740).
- CVE-2018-8956: Fixed an issue which could have allowed remote attackers to prevent a broadcast client from synchronizing its clock with a broadcast NTP server via spoofed mode 3 and mode 5 packets (bsc#1171355).
- CVE-2020-13817: Fixed an issue which an off-path attacker with the ability to query time from victim's ntpd instance could have modified the victim's clock by a limited amount (bsc#1172651).
- CVE-2020-15025: Fixed an issue which remote attacker could have caused denial of service by consuming the memory when a CMAC key was used andassociated with a CMAC algorithm in the ntp.keys (bsc#1173334).
- Removed an OpenSSL version warning (bsc#992038 and bsc#1125401).
- Record
SUSE-SU-2020:1823-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
ntpDebian:11 |
before 1:4.2.8p14+dfsg-1 | 1:4.2.8p14+dfsg-1 |
ntpSUSE:Linux Enterprise Server 11 SP4-LTSS |
before 4.2.8p15-64.16.1 | 4.2.8p15-64.16.1 |
ntpSUSE:HPE Helion OpenStack 8 |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:OpenStack Cloud 7 |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:OpenStack Cloud 8 |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:OpenStack Cloud Crowbar 8 |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:Linux Enterprise Server for SAP Applications 12 SP2 |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:Linux Enterprise Server for SAP Applications 12 SP3 |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:Linux Enterprise Server 12 SP2-LTSS |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:Linux Enterprise Server 12 SP2-BCL |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
Show 19 moreShow less
| Package | Affected | Fixed |
|---|---|---|
ntpSUSE:Linux Enterprise Server 12 SP3-LTSS |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:Linux Enterprise Server 12 SP3-BCL |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:Linux Enterprise Server 12 SP4 |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:Linux Enterprise Server for SAP Applications 12 SP4 |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:Linux Enterprise Server 12 SP5 |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:Linux Enterprise Server for SAP Applications 12 SP5 |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:Enterprise Storage 5 |
before 4.2.8p15-88.1 | 4.2.8p15-88.1 |
ntpSUSE:Linux Enterprise Module for Legacy 15 SP1 |
before 4.2.8p15-4.10.1 | 4.2.8p15-4.10.1 |
ntpSUSE:Linux Enterprise Module for Legacy 15 SP2 |
before 4.2.8p15-4.10.1 | 4.2.8p15-4.10.1 |
ntpSUSE:Linux Enterprise Server 15-LTSS |
before 4.2.8p15-4.10.1 | 4.2.8p15-4.10.1 |
ntpSUSE:Linux Enterprise Server for SAP Applications 15 |
before 4.2.8p15-4.10.1 | 4.2.8p15-4.10.1 |
ntpUbuntu:Pro:14.04:LTS |
All versions, plus listed versions 1:4.2.6.p5+dfsg-3ubuntu21:4.2.6.p5+dfsg-3ubuntu2.14.04.11:4.2.6.p5+dfsg-3ubuntu2.14.04.21:4.2.6.p5+dfsg-3ubuntu2.14.04.31:4.2.6.p5+dfsg-3ubuntu2.14.04.5 Show 8 moreShow less1:4.2.6.p5+dfsg-3ubuntu2.14.04.61:4.2.6.p5+dfsg-3ubuntu2.14.04.71:4.2.6.p5+dfsg-3ubuntu2.14.04.81:4.2.6.p5+dfsg-3ubuntu2.14.04.101:4.2.6.p5+dfsg-3ubuntu2.14.04.111:4.2.6.p5+dfsg-3ubuntu2.14.04.121:4.2.6.p5+dfsg-3ubuntu2.14.04.131:4.2.6.p5+dfsg-3ubuntu2.14.04.13+esm1 |
None known |
ntpUbuntu:16.04:LTS |
All versions, plus listed versions 1:4.2.6.p5+dfsg-3ubuntu81:4.2.6.p5+dfsg-3ubuntu8.11:4.2.6.p5+dfsg-3ubuntu91:4.2.8p4+dfsg-3ubuntu11:4.2.8p4+dfsg-3ubuntu2 Show 13 moreShow less1:4.2.8p4+dfsg-3ubuntu31:4.2.8p4+dfsg-3ubuntu41:4.2.8p4+dfsg-3ubuntu51:4.2.8p4+dfsg-3ubuntu5.11:4.2.8p4+dfsg-3ubuntu5.21:4.2.8p4+dfsg-3ubuntu5.31:4.2.8p4+dfsg-3ubuntu5.41:4.2.8p4+dfsg-3ubuntu5.51:4.2.8p4+dfsg-3ubuntu5.61:4.2.8p4+dfsg-3ubuntu5.71:4.2.8p4+dfsg-3ubuntu5.81:4.2.8p4+dfsg-3ubuntu5.91:4.2.8p4+dfsg-3ubuntu5.10 |
None known |
ntpUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 1:4.2.8p10+dfsg-5ubuntu31:4.2.8p10+dfsg-5ubuntu41:4.2.8p10+dfsg-5ubuntu51:4.2.8p10+dfsg-5ubuntu61:4.2.8p10+dfsg-5ubuntu7 Show 7 moreShow less1:4.2.8p10+dfsg-5ubuntu7.11:4.2.8p10+dfsg-5ubuntu7.1+esm11:4.2.8p10+dfsg-5ubuntu7.1+esm21:4.2.8p10+dfsg-5ubuntu7.21:4.2.8p10+dfsg-5ubuntu7.2+esm11:4.2.8p10+dfsg-5ubuntu7.31:4.2.8p10+dfsg-5ubuntu7.3+esm1 |
None known |
ntpUbuntu:Pro:20.04:LTS |
All versions, plus listed versions 1:4.2.8p12+dfsg-3ubuntu21:4.2.8p12+dfsg-3ubuntu31:4.2.8p12+dfsg-3ubuntu41:4.2.8p12+dfsg-3ubuntu4.20.04.11:4.2.8p12+dfsg-3ubuntu4.20.04.1+esm1 |
None known |
ntpUbuntu:22.04:LTS |
All versions, plus listed versions 1:4.2.8p12+dfsg-3ubuntu61:4.2.8p15+dfsg-1ubuntu11:4.2.8p15+dfsg-1ubuntu2 |
None known |
ntpopenSUSE:Leap 15.1 |
before 4.2.8p15-lp151.2.3.1 | 4.2.8p15-lp151.2.3.1 |
ntpopenSUSE:Leap 15.2 |
before 4.2.8p15-lp152.3.3.1 | 4.2.8p15-lp152.3.3.1 |
ntpopenSUSE:Tumbleweed |
before 4.2.8p15-7.2 | 4.2.8p15-7.2 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2018-8956 is a medium vulnerability (CVSS 5.3) in Ntp, published May 6, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 3.14%, the 87th percentile. Fixed in ntp 1:4.2.8p14+dfsg-1.
References
ntp.org
tools.ietf.org/html/rfc5905
nikhiltripathi.in/NTP_attack.pdf
arxiv.org/abs/2005.01783
security.netapp.com/advisory/ntap-20200518-0006
lists.opensuse.org/opensuse-security-announce/2020-07/msg00005.html
Show 35 moreShow less
nvd.nist.gov/vuln/detail/CVE-2018-8956
github.com/advisories/GHSA-gg7p-jc5w-p68m
security-tracker.debian.org/tracker/CVE-2018-8956
suse.com/support/update/announcement/2020/suse-su-202014415-1
bugzilla.suse.com/1169740
ubuntu.com/security/CVE-2018-8956
cve.org/CVERecord?id=CVE-2018-8956