CVE-2016-6171: Knot DNS before 2.3.0 allows remote DNS servers to cause a denial of service (memory exhaustion and slave serv

Q: How do I fix CVE-2016-6171?

knot dns: upgrade to 2.3.0. Exact commands for each OS are on this page.

Q: Is CVE-2016-6171 being exploited?

CVE-2016-6171 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2016-6171 affect?

CVE-2016-6171 affects knot dns. Severity is high (CVSS 8.6). Knot DNS before 2.3.0 allows remote DNS servers to cause a denial of service (memory exhaustion and slave server crash) via a large zone transfer for (1) DDNS, (2) AXFR, or (3) IXFR.

Q: How urgent is CVE-2016-6171?

Priority 57/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 8.6REMOTEUPGRADE

CVE-2016-6171 is a high-severity flaw (CVSS 8.6) affecting knot dns. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Knot DNS before 2.3.0 allows remote DNS servers to cause a denial of service (memory exhaustion and slave server crash) via a large zone transfer for (1) DDNS, (2) AXFR, or (3) IXFR.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.6 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.8% (top 14%)
CISA exploited list	No
Weakness	CWE-400
Published	2017-02-09
Last modified	2026-06-17

Publisher (CNA): Red Hat, Inc. · Vendor: knot-dns

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

Am I affected?

Timeline

2017-02-09 15:59 UTCPublished CVE record published
2026-06-17 00:50 UTCUpdated Record last modified

knot-dns knot dns UPGRADE

Affected: < 2.3.0

Fixed in: 2.3.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy knot-dns || rpm -q knot-dns || knot-dns --version

2. UPGRADE to 2.3.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade knot-dns

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade knot-dns

Note

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

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-2016-6171?

knot dns: upgrade to 2.3.0. Exact commands for each OS are on this page.

Is CVE-2016-6171 being exploited?

CVE-2016-6171 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-2016-6171 affect?

CVE-2016-6171 affects knot dns. Severity is high (CVSS 8.6). Knot DNS before 2.3.0 allows remote DNS servers to cause a denial of service (memory exhaustion and slave server crash) via a large zone transfer for (1) DDNS, (2) AXFR, or (3) IXFR.

How urgent is CVE-2016-6171?

Priority 57/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2017-11104 MEDIUM 5.9 UPGRADE MITIGATE Knot DNS before 2.4.5 and 2.5.x before 2.5.2 contains a flaw within the TSIG protocol implementation that woul

References

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