CVE-2026-33254
Received Received - Intake
Denial of Service via Memory Exhaustion in DNSdist DoQ/DoH

Publication date: 2026-04-22

Last updated on: 2026-04-27

Assigner: Open-Xchange

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.
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Meta Information
Published
2026-04-22
Last Modified
2026-04-27
Generated
2026-06-16
AI Q&A
2026-04-22
EPSS Evaluated
2026-06-15
NVD
CVE-2026-33254
EUVD
EUVD-2026-24927
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
powerdns dnsdist From 1.9.0 (inc) to 1.9.13 (exc)
powerdns dnsdist From 2.0.0 (inc) to 2.0.4 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-770 The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
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Executive Summary

This vulnerability allows an attacker to create a large number of concurrent DNS over QUIC (DoQ) or DNS over HTTP/3 (DoH3) connections to the DNSdist service. This causes unlimited memory allocation within DNSdist, which can lead to a denial of service condition.

It is important to note that both DoQ and DoH3 are disabled by default in DNSdist.

Impact Analysis

The primary impact of this vulnerability is a denial of service (DoS) attack against the DNSdist service. An attacker exploiting this issue can cause the service to consume unlimited memory, potentially leading to service crashes or unavailability.

Mitigation Strategies

Since DOQ and DoH3 are disabled by default, ensure that these protocols remain disabled if not needed.

Monitor and limit the number of concurrent DoQ or DoH3 connections to prevent excessive memory allocation.

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