CVE-2020-13817: ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows remote attackers to cause a denial of service (dae

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HIGH 7.4REMOTEUPGRADEMITIGATEMITIGATE

CVE-2020-13817 is a high-severity flaw (CVSS 7.4) affecting ntp, cloud backup, clustered data ontap. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows remote attackers to cause a denial of service (daemon exit or system time change) by predicting transmit timestamps for use in spoofed packets. The victim must be relying on unauthenticated IPv4 time sources. There must be an off-path attacker who can query time from the victim's ntpd instance.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.4 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	3.4% (top 11%)
CISA exploited list	No
Weakness	CWE-330
Published	2020-06-04
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: netapp · ntp

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-06-04 13:15 UTCPublished CVE record published
2026-06-17 02:53 UTCUpdated Record last modified

ntp ntp UPGRADE

Affected: < 4.2.8 · >= 4.3.0 and < 4.3.100 · 4.2.8 · 4.2.8 p1 · 4.2.8 p1-beta1 · 4.2.8 p1-beta2 · 4.2.8 p1-beta3 · 4.2.8 p1-beta4

Fixed in: 4.2.8, 4.3.100

Safe to downgrade to: a release before 4.2.8

1. Check installed version

apt-cache policy ntp || rpm -q ntp || ntp --version

2. UPGRADE to 4.2.8 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade ntp

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ntp

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 4.2.8 (Debian / Ubuntu)

apt-cache madison ntp sudo apt install ntp=<VERSION_BEFORE_4.2.8> sudo apt-mark hold ntp

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list ntp sudo dnf downgrade ntp-<VERSION_BEFORE_4.2.8> sudo dnf versionlock add ntp

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

netapp cloud backup MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy cloud-backup || rpm -q cloud-backup || cloud-backup --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

netapp clustered data ontap MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy clustered-data-ontap || rpm -q clustered-data-ontap || clustered-data-ontap --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

netapp data ontap MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy data-ontap || rpm -q data-ontap || data-ontap --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

netapp element software MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy element-software || rpm -q element-software || element-software --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

netapp hci management node MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy hci-management-node || rpm -q hci-management-node || hci-management-node --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-13817?

ntp: upgrade to 4.2.8, 4.3.100; cloud backup: mitigate or apply the listed mitigation; clustered data ontap: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-13817 being exploited?

CVE-2020-13817 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-13817 affect?

CVE-2020-13817 affects ntp, cloud backup, clustered data ontap. Severity is high (CVSS 7.4). ntpd in ntp before 4.2.8p14 and 4.3.x before 4.3.100 allows remote attackers to cause a denial of service (daemon exit or system time change) by predicting transmit timestamps for use in spoofed packets. The victim must be relying on unauth

How urgent is CVE-2020-13817?

Priority 53/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2023-26555 MEDIUM 6.4 DOWNGRADE praecis_parse in ntpd/refclock_palisade.c in NTP 4.2.8p15 has an out-of-bounds write
CVE-2023-26554 MEDIUM 5.6 DOWNGRADE mstolfp in libntp/mstolfp.c in NTP 4.2.8p15 has an out-of-bounds write when adding a '\0' character
CVE-2023-26553 MEDIUM 5.6 DOWNGRADE mstolfp in libntp/mstolfp.c in NTP 4.2.8p15 has an out-of-bounds write when copying the trailing number
CVE-2023-26552 MEDIUM 5.6 DOWNGRADE mstolfp in libntp/mstolfp.c in NTP 4.2.8p15 has an out-of-bounds write when adding a decimal point
CVE-2023-26551 MEDIUM 5.6 DOWNGRADE mstolfp in libntp/mstolfp.c in NTP 4.2.8p15 has an out-of-bounds write in the cp<cpdec while loop

References

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