CVE-2026-47184

Zeroconf: Unbounded DNS record cache allows LAN-local memory exhaustion via multicast flood

Published Jul 17, 2026 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
Description
Zeroconf is a pure Python implementation of multicast DNS service discovery. Prior to 0.149.7, DNSCache._async_add inserted every response record into cache, _expirations, _expire_heap, and service_cache without a cap, allowing unauthenticated hosts on the local link over UDP/5353 (224.0.0.251 / ff02::fb) to multicast valid mDNS responses with unique names and cause memory exhaustion, slower cache lookups, slower async_expire passes, and broken discovery, registration, and ServiceBrowser callbacks. This issue is fixed in version 0.149.7.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-rfg2-pjw2-56x2 zeroconf has unbounded DNS record cache that allows LAN-local memory exhaustion via multicast flood
History
Type Values Removed Values Added
First Time appeared Paulsm
Paulsm zeroconf
CPEs cpe:2.3:a:paulsm:zeroconf:*:*:*:*:*:python:*:*
Vendors & Products Paulsm
Paulsm zeroconf
Type Values Removed Values Added
First Time appeared Python-zeroconf
Python-zeroconf python-zeroconf
Vendors & Products Python-zeroconf
Python-zeroconf python-zeroconf
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Zeroconf is a pure Python implementation of multicast DNS service discovery. Prior to 0.149.7, DNSCache._async_add inserted every response record into cache, _expirations, _expire_heap, and service_cache without a cap, allowing unauthenticated hosts on the local link over UDP/5353 (224.0.0.251 / ff02::fb) to multicast valid mDNS responses with unique names and cause memory exhaustion, slower cache lookups, slower async_expire passes, and broken discovery, registration, and ServiceBrowser callbacks. This issue is fixed in version 0.149.7.
Title Zeroconf: Unbounded DNS record cache allows LAN-local memory exhaustion via multicast flood
Weaknesses CWE-770
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jul 21, 2026, 1:50 AM
Reserved
May 18, 2026, 10:07 PM
Status
Analyzed
Published
Jul 17, 2026, 7:17 PM
Modified
Aug 17, 2026, 7:56 PM
Severity
Moderate
Public date
Jul 17, 2026, 6:25 PM