Description
Zeroconf 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.
Affected products
paulsm: zeroconf
References4
- github.com/python-zeroconf/python-zeroconf/security/advisories/… Vendor AdvisoryPatch
- github.com/python-zeroconf/python-zeroconf/commit/f9e23592137f3… Patch
- github.com/python-zeroconf/python-zeroconf/pull/1719 Issue TrackingPatch
- github.com/python-zeroconf/python-zeroconf/releases/tag/0.149.5 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: 31 · as of 14 November 2026
- CWE
- CWE-674
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