CVE-2026-33595 DoQ/DoH3 excessive memory allocation

Medium 5.3 Published 22 Apr 2026 Updated 22 Apr 2026

A remote attacker can cause denial of service by triggering excessive memory allocation via error responses in PowerDNS DNSdist.

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

What is CVE-2026-33595?

CVE-2026-33595 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

A client can trigger excessive memory allocation by generating a lot of errors responses over a single DoQ and DoH3 connection, as some resources were not properly released until the end of the connection.

Weakness: CWE-770

Which versions are affected by CVE-2026-33595?

It affects 1 product.

Products include Powerdns Dnsdist.

How do I fix CVE-2026-33595?

Upgrade to a fixed version.

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-2026-33595 being exploited?

There is no known exploitation of CVE-2026-33595 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2026-33595, GHSA-6482-x4xv-9qvm, UBUNTU-CVE-2026-33595.