CVE-2026-42255 Denial of service in DnsServer

High 7.2 Published 26 Apr 2026 Updated 27 Apr 2026

Attackers can cause DNS traffic amplification and denial of service via cyclic name server delegation in Technitium DNS Server.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-42255?

CVE-2026-42255 is a high-severity denial of service vulnerability in Technitium DnsServer, published on 26 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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

Weakness: CWE-684

Which versions are affected by CVE-2026-42255?

It affects 1 product.

Products include Technitium Dnsserver.

How do I fix CVE-2026-42255?

No fix has been published for CVE-2026-42255 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-42255 being exploited?

There is no known exploitation of CVE-2026-42255 in the wild and no public exploit code.

Sources

Also known as GHSA-v7f3-6mf2-m8hj.