CVE-2026-42255: Technitium DNS Server before 15.0 allows DNS traffic amplification via cyclic name server delegation.

Q: How do I fix CVE-2026-42255?

dnsserver: upgrade to 15.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-42255 being exploited?

CVE-2026-42255 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-2026-42255 affect?

CVE-2026-42255 affects dnsserver. Severity is high (CVSS 7.2). Technitium DNS Server before 15.0 allows DNS traffic amplification via cyclic name server delegation.

Q: How urgent is CVE-2026-42255?

Priority 33/100. High severity; Remotely exploitable, no login, no user action

Routine

HIGH 7.2REMOTEUPGRADE

CVE-2026-42255 is a high-severity flaw (CVSS 7.2) affecting dnsserver. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Technitium DNS Server before 15.0 allows DNS traffic amplification via cyclic name server delegation.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.2 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 89%)
CISA exploited list	No
Weakness	CWE-684
Published	2026-04-26
Last modified	2026-10-26

Publisher (CNA): MITRE · Vendor: technitium

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-26 04:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

technitium dnsserver UPGRADE

Affected: < 15.0

Fixed in: 15.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 15.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade dnsserver

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-2026-42255?

dnsserver: upgrade to 15.0. Exact commands for each OS are on this page.

Is CVE-2026-42255 being exploited?

CVE-2026-42255 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-2026-42255 affect?

CVE-2026-42255 affects dnsserver. Severity is high (CVSS 7.2). Technitium DNS Server before 15.0 allows DNS traffic amplification via cyclic name server delegation.

How urgent is CVE-2026-42255?

Priority 33/100. High severity; Remotely exploitable, no login, no user action

References

← Back to latest CVEs