VulnerabilityDeferred

CVE-2026-40211

An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away.

MEDIUM 5.3EPSS 0.30%

Does this matter?

Lower severity and a low EPSS score (0.30%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 3.1: 5.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS: 0.30% probability · 22th percentile
CISA KEV: Not listed
Weakness: CWE-770
Source: security@open-xchange.com

References

https://www.dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2026-09.html

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.