CVE-2026-40211

Denial of service via crafted DoH3 queries

Published Jun 25, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory condition, resulting in a denial of service.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DSA Debian DSA DSA-6367-1 dnsdist security update
History
Type Values Removed Values Added
First Time appeared Powerdns
Powerdns dnsdist
Vendors & Products Powerdns
Powerdns dnsdist
Type Values Removed Values Added
Weaknesses CWE-770
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory condition, resulting in a denial of service.
Title Denial of service via crafted DoH3 queries
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
OX
Published
Updated
Jun 25, 2026, 1:45 PM
Reserved
Apr 10, 2026, 7:11 AM
Status
Deferred
Published
Jun 25, 2026, 1:16 PM
Modified
Oct 25, 2026, 11:10 PM