Zeroconf: Unbounded recursion in DNS compression-pointer decoder allows LAN-local denial of service

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Summary

CVECVE-2026-47180
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-17 19:17:15 UTC
Updated2026-07-17 20:17:18 UTC
DescriptionZeroconf is a pure Python implementation of multicast DNS service discovery. Prior to 0.149.5, DNSIncoming._decode_labels_at_offset recurses once per DNS-name compression pointer, and a single mDNS packet carrying chained pointers can trigger a RecursionError that escapes DNSIncoming.__init__, causing sustained CPU burn, log flooding, and degraded mDNS-dependent features for unauthenticated hosts on the local link over UDP/5353 (224.0.0.251 / ff02::fb). This issue is fixed in version 0.149.5.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

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

Problem Types: CWE-674 | CWE-674 CWE-674: Uncontrolled Recursion

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED6.5MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Python-zeroconf Python-zeroconf affected < 0.149.5 Not specified

References

ReferenceSourceLinkTags
github.com/python-zeroconf/python-zeroconf/commit/f9e23592137f30fdf7ef71... [email protected] github.com
github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-9pgc... [email protected] github.com
github.com/python-zeroconf/python-zeroconf/releases/tag/0.149.5 [email protected] github.com
github.com/python-zeroconf/python-zeroconf/pull/1719 [email protected] github.com
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