CVE-2016-2518: The MATCH_ASSOC function in NTP before version 4.2.8p9 and 4.3.x before 4.3.92 allows remote attackers to caus

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MEDIUM 5.3REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2016-2518 is a medium-severity flaw (CVSS 5.3) affecting ntp, debian linux, clustered data ontap. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The MATCH_ASSOC function in NTP before version 4.2.8p9 and 4.3.x before 4.3.92 allows remote attackers to cause an out-of-bounds reference via an addpeer request with a large hmode value.

Why this priority

EPSS top 3%: very likely to be exploited
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	15.1% (top 3%)
CISA exploited list	No
Weakness	CWE-125
Published	2017-01-30
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2017-01-30 21:59 UTCPublished CVE record published
2026-06-17 00:44 UTCUpdated Record last modified

ntp ntp UPGRADE

Affected: < 4.2.8 · >= 4.3.0 and < 4.3.92 · 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, 4.3.92

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.

debian debian linux MITIGATE

Affected: 8.0 · 9.0 · 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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 oncommand balance 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 oncommand-balance || rpm -q oncommand-balance || oncommand-balance --version

No fixed or unaffected release known

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

netapp oncommand performance manager 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 oncommand-performance-manager || rpm -q oncommand-performance-manager || oncommand-performance-manager --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-2016-2518?

ntp: upgrade to 4.2.8, 4.3.92; debian linux: 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-2016-2518 being exploited?

CVE-2016-2518 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-2016-2518 affect?

CVE-2016-2518 affects ntp, debian linux, clustered data ontap. Severity is medium (CVSS 5.3). The MATCH_ASSOC function in NTP before version 4.2.8p9 and 4.3.x before 4.3.92 allows remote attackers to cause an out-of-bounds reference via an addpeer request with a large hmode value.

How urgent is CVE-2016-2518?

Priority 53/100. EPSS top 3%: very likely to be exploited; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities

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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