CVE-2026-33254 Resource exhaustion via DoQ/DoH3 connections

Medium 5.3 Published 22 Apr 2026 Updated 22 Apr 2026

Attackers can cause denial of service via memory exhaustion in DNSdist when DoQ or DoH3 are enabled, requiring administrators to apply patches or disable features.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-33254?

CVE-2026-33254 is a medium-severity denial of service vulnerability in PowerDNS DNSdist, published on 22 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

An attacker can create a large number of concurrent DoQ or DoH3 connections, causing unlimited memory allocation in DNSdist and leading to a denial of service. DOQ and DoH3 are disabled by default.

Weakness: CWE-770

Which versions are affected by CVE-2026-33254?

It affects 1 product.

Products include Powerdns Dnsdist.

How do I fix CVE-2026-33254?

Apply the vendor's patch.

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-2026-33254 being exploited?

There is no known exploitation of CVE-2026-33254 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2026-33254, GHSA-wgv5-fpv8-m4jc, UBUNTU-CVE-2026-33254.