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CVE-2020-11868

ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows an off-path attacker to block...

5.9 MediumFix available

ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows an off-path attacker to block unauthenticated synchronization via a server mode packet with a spoofed source IP address, because transmissions are rescheduled even when a packet lacks a valid origin timestamp.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

2.12%Up 0.5 points since Apr 14, 2021
90%50%10%1%

What each source reports

CVE List 7.5

ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows an off-path attacker to block unauthenticated synchronization via a server mode packet with a spoofed source IP address, because transmissions are rescheduled even when a packet lacks a valid origin timestamp.

Record
CVE-2020-11868
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.0
5.9 MediumCVSS:3.0/AC:H/AV:N/A:H/C:N/I:N/PR:N/S:U/UI:N
Weakness
CWE-346
Updated
2026-11-02
EUVDEUVD-2020-4208 7.5

ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows an off-path attacker to block unauthenticated synchronization via a server mode packet with a spoofed source IP address, because transmissions are rescheduled even when a packet lacks a valid origin timestamp.

Record
EUVD-2020-4208
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-57qq-hwp2-xmcj 7.5

ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows an off-path attacker to block...

ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows an off-path attacker to block unauthenticated synchronization via a server mode packet with a spoofed source IP address, because transmissions are rescheduled even when a packet lacks a valid origin timestamp.

Record
GHSA-57qq-hwp2-xmcj
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-346, CWE-400
Updated
2026-11-02
NVD 7.5

ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows an off-path attacker to block unauthenticated synchronization via a server mode packet with a spoofed source IP address, because transmissions are rescheduled even when a packet lacks a valid origin timestamp.

Record
CVE-2020-11868
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.0
5.9 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness
CWE-346
Updated
2026-11-02
OSV 7.5

ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows an off-path attacker to block unauthenticated synchronization via a server mode packet with a spoofed source IP address, because transmissions are rescheduled even when a packet lacks a valid origin timestamp.

Record
CVE-2020-11868
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2020-11868 7.5

ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows an off-path attacker to block unauthenticated synchronization via a server mode packet with a spoofed source IP address, because transmissions are rescheduled even when a packet lacks a valid origin timestamp.

Record
DEBIAN-CVE-2020-11868
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 11 moreShow less
OSVRHSA-2020:2663 7.4

Red Hat Security Advisory: ntp security update

Record
RHSA-2020:2663
CVSS 3.1
7.4 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2020-11868 7.5

ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows an off-path attacker to block unauthenticated synchronization via a server mode packet with a spoofed source IP address, because transmissions are rescheduled even when a packet lacks a valid origin timestamp.

Record
UBUNTU-CVE-2020-11868
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 3.0
5.9 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVCLSA-2021-1633442934 No score

Fix of CVE: CVE-2020-11868

  • CVE-2020-11868: incorrect handling of packets from unauthenticated synchronization source with spoofed IP address leads to denial of service.
Record
CLSA-2021-1633442934
Updated
2026-11-02
OSVCLSA-2021-1634922835 No score

Fixed CVE-2020-11868 in ntp

  • CVE-2020-11868: incorrect handling of packets from unauthenticated synchronization source with spoofed IP address leads to denial of service.
Record
CLSA-2021-1634922835
Updated
2026-11-02
OSVMGASA-2020-0212 No score

Updated ntp packages fix security vulnerability

The updated packages fix security vulnerabilities including:

ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows an off-path attacker to block unauthenticated synchronization via a server mode packet with a spoofed source IP address, because transmissions are rescheduled even when a packet lacks a valid origin timestamp. (CVE-2020-11868)

Record
MGASA-2020-0212
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

Show 5 moreShow less

Affected packages

Affected packages
PackageAffectedFixed
ntp
TuxCare:CentOS:6
before 4.2.6p5-16.el6.cloudlinux.els
4.2.6p5-16.el6.cloudlinux.els
ntp-doc
TuxCare:CentOS:6
before 4.2.6p5-16.el6.cloudlinux.els
4.2.6p5-16.el6.cloudlinux.els
ntp-perl
TuxCare:CentOS:6
before 4.2.6p5-16.el6.cloudlinux.els
4.2.6p5-16.el6.cloudlinux.els
ntpdate
TuxCare:CentOS:6
before 4.2.6p5-16.el6.cloudlinux.els
4.2.6p5-16.el6.cloudlinux.els
ntp
TuxCare:OracleLinux:6
before 4.2.6p5-16.el6.cloudlinux.els
4.2.6p5-16.el6.cloudlinux.els
ntp-doc
TuxCare:OracleLinux:6
before 4.2.6p5-16.el6.cloudlinux.els
4.2.6p5-16.el6.cloudlinux.els
ntp-perl
TuxCare:OracleLinux:6
before 4.2.6p5-16.el6.cloudlinux.els
4.2.6p5-16.el6.cloudlinux.els
ntpdate
TuxCare:OracleLinux:6
before 4.2.6p5-16.el6.cloudlinux.els
4.2.6p5-16.el6.cloudlinux.els
ntp
Debian:11
before 1:4.2.8p14+dfsg-1
1:4.2.8p14+dfsg-1
ntp
Debian:8
before 1:4.2.6.p5+dfsg-7+deb8u3, plus listed versions
1:4.2.6.p5+dfsg-71:4.2.6.p5+dfsg-7+deb8u11:4.2.6.p5+dfsg-7+deb8u2
1:4.2.6.p5+dfsg-7+deb8u3
Show 53 moreShow less
Affected packages
PackageAffectedFixed
ntp
Mageia:7
before 4.2.8p14-1.mga7
4.2.8p14-1.mga7
ntp
Red Hat:enterprise_linux:7::client
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp-debuginfo
Red Hat:enterprise_linux:7::client
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntpdate
Red Hat:enterprise_linux:7::client
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp-doc
Red Hat:enterprise_linux:7::client
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp-perl
Red Hat:enterprise_linux:7::client
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
sntp
Red Hat:enterprise_linux:7::client
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp
Red Hat:enterprise_linux:7::computenode
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp-debuginfo
Red Hat:enterprise_linux:7::computenode
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntpdate
Red Hat:enterprise_linux:7::computenode
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp-doc
Red Hat:enterprise_linux:7::computenode
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp-perl
Red Hat:enterprise_linux:7::computenode
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
sntp
Red Hat:enterprise_linux:7::computenode
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp
Red Hat:enterprise_linux:7::server
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp-debuginfo
Red Hat:enterprise_linux:7::server
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntpdate
Red Hat:enterprise_linux:7::server
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp-doc
Red Hat:enterprise_linux:7::server
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp-perl
Red Hat:enterprise_linux:7::server
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
sntp
Red Hat:enterprise_linux:7::server
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp
Red Hat:enterprise_linux:7::workstation
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp-debuginfo
Red Hat:enterprise_linux:7::workstation
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntpdate
Red Hat:enterprise_linux:7::workstation
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp-doc
Red Hat:enterprise_linux:7::workstation
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp-perl
Red Hat:enterprise_linux:7::workstation
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
sntp
Red Hat:enterprise_linux:7::workstation
before 0:4.2.6p5-29.el7_8.2
0:4.2.6p5-29.el7_8.2
ntp
SUSE:Linux Enterprise Server 11 SP4-LTSS
before 4.2.8p15-64.16.1
4.2.8p15-64.16.1
ntp
SUSE:HPE Helion OpenStack 8
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:OpenStack Cloud 7
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:OpenStack Cloud 8
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:OpenStack Cloud Crowbar 8
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:Linux Enterprise Server for SAP Applications 12 SP2
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:Linux Enterprise Server for SAP Applications 12 SP3
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:Linux Enterprise Server 12 SP2-LTSS
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:Linux Enterprise Server 12 SP2-BCL
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:Linux Enterprise Server 12 SP3-LTSS
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:Linux Enterprise Server 12 SP3-BCL
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:Linux Enterprise Server 12 SP4
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:Linux Enterprise Server for SAP Applications 12 SP4
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:Linux Enterprise Server 12 SP5
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:Linux Enterprise Server for SAP Applications 12 SP5
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:Enterprise Storage 5
before 4.2.8p15-88.1
4.2.8p15-88.1
ntp
SUSE:Linux Enterprise Module for Legacy 15 SP1
before 4.2.8p15-4.10.1
4.2.8p15-4.10.1
ntp
SUSE:Linux Enterprise Module for Legacy 15 SP2
before 4.2.8p15-4.10.1
4.2.8p15-4.10.1
ntp
SUSE:Linux Enterprise Server 15-LTSS
before 4.2.8p15-4.10.1
4.2.8p15-4.10.1
ntp
SUSE:Linux Enterprise Server for SAP Applications 15
before 4.2.8p15-4.10.1
4.2.8p15-4.10.1
ntp
Ubuntu: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 less
1:4.2.6.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
ntp
Ubuntu: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 less
1:4.2.8p4+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
ntp
Ubuntu: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 less
1:4.2.8p10+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
ntp
Ubuntu: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
ntp
Ubuntu: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
ntp
openSUSE:Leap 15.1
before 4.2.8p15-lp151.2.3.1
4.2.8p15-lp151.2.3.1
ntp
openSUSE:Leap 15.2
before 4.2.8p15-lp152.3.3.1
4.2.8p15-lp152.3.3.1
ntp
openSUSE:Tumbleweed
before 4.2.8p15-7.2
4.2.8p15-7.2

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-11868 is a medium vulnerability (CVSS 5.9) in Ntp, published April 17, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.12%, the 81st percentile. Fixed in ntp 4.2.6p5-16.el6.cloudlinux.els.

References

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