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.
Affected products
paulsm: zeroconf
References5
- github.com/python-zeroconf/python-zeroconf/security/advisories/… Vendor AdvisoryPatch
- github.com/python-zeroconf/python-zeroconf/commit/0ad3f37b5b852… Patch
- github.com/python-zeroconf/python-zeroconf/issues/1715 Issue TrackingPatch
- github.com/python-zeroconf/python-zeroconf/pull/1718 Issue TrackingPatch
- github.com/python-zeroconf/python-zeroconf/releases/tag/0.149.7 Release Notes
Metrics
- CVSS 3.1
-
6.5
MEDIUM
Score source: CNA
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 0% percentile: 34 · as of 14 November 2026
- CWE
- CWE-770
Could this be exploited in your environment?
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