🛡️ CVE-2026-40211

🟡 CVSS 5.3 — Medium ✅ No Known Exploit CWE-770 NVD
5.3
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability low.

Weakness class

CVE-2026-40211 is classified as CWE-770: Allocation of Resources Without Limits. Resources are allocated on request with no cap, so a client can exhaust them.

Affected software

CVE-2026-40211 is recorded against 1 package.

  • unknown

Timeline and source

Published on 25 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

www.dnsdist.org

Details

Severity MEDIUM
CVSS Score 5.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CWE CWE-770
Public Exploit ✅ No
Source NVD
Published 2026-06-25
Updated 2026-08-11
Modified 2026-06-25
Fix URL N/A

Affected Packages

Software From version Fixed in
unknown — —

Similar Threats

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