Denial of service via IXFR queries

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-40209
StatePUBLISHED
AssignerOX
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-25 13:16:39 UTC
Updated2026-06-25 15:59:47 UTC
DescriptionAn 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.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

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

EPSS: 0.004040000 probability, percentile 0.322920000 (date 2026-06-29)

Problem Types: CWE-772 | Missing Release of Resource after Effective Lifetime | CWE-772 CWE-772 Missing Release of Resource after Effective Lifetime

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNACVSS5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA PowerDNS DNSdist affected 1.9.0 1.9.15 semver Not specified
CNA PowerDNS DNSdist affected 2.0.0 2.0.7 semver Not specified

References

ReferenceSourceLinkTags
www.dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2026-09.html [email protected] www.dnsdist.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Qifan Zhang (Palo Alto Networks) (en)

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