CVE-2026-40209 — MEDIUM (5.3)

Vulnerability 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.

CVSS Score

5.3

MEDIUM

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

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

NONE

Integrity

NONE

Availability

LOW

Related Weaknesses (CWE)

CWE-772

References

https://www.dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2026-0

FAQ

What is CVE-2026-40209?

CVE-2026-40209 is a vulnerability with a CVSS score of 5.3 (MEDIUM). 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 ...

How severe is CVE-2026-40209?

CVE-2026-40209 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-40209?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.