5.3
MEDIUM CVSS 3.1
CVE-2026-40211
Denial of service via crafted DoH3 queries
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.

INFO

Published Date :

June 25, 2026, 12:23 p.m.

Last Modified :

June 25, 2026, 12:23 p.m.

Remotely Exploit :

Yes !

Source :

OX
Affected Products

The following products are affected by CVE-2026-40211 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Powerdns dnsdist
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 MEDIUM 8ce71d90-2354-404b-a86e-bec2cc4e6981
CVSS 3.1 MEDIUM [email protected]
Solution
Update software to fix buffer freeing issue and prevent memory exhaustion.
  • Update the affected software to the latest version.
  • Apply vendor patches for buffer handling.
  • Monitor memory usage on critical systems.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-40211 vulnerability anywhere in the article.

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.