CVE-2026-40209

Name: CVE-2026-40209
Creator: NVD / NIST
Published: 2026-06-25T13:16:39.527+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 0.40%

Last modified Jun 25, 2026

CVE-2026-40209 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. An attacker might be able to cause outgoing TCP connections to backend to be stuck until a timeout occurs instead of being released immediately, by sending IXFR queries. This could be used to cause a denial of service if there is a limit to the number of concurrent connections to this backend, or if the process runs out of file descriptors.. EPSS estimates a 0.40% chance of exploitation in the next 30 days.

Description

An attacker might be able to cause outgoing TCP connections to backend to be stuck until a timeout occurs instead of being released immediately, by sending IXFR queries. This could be used to cause a denial of service if there is a limit to the number of concurrent connections to this backend, or if the process runs out of file descriptors.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS Probability

0.40%

32.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-772

References

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

Timeline

Published: Jun 25, 2026
Last Modified: Jun 25, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-40209?

How severe is CVE-2026-40209?

CVE-2026-40209 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.40% probability of exploitation in the next 30 days.

How do I fix CVE-2026-40209?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-40209?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST