CVE-2026-47180
Zeroconf: Unbounded recursion in DNS compression-pointer decoder allows LAN-local denial of service
- State
- Published
- Severity
- 6.5 Medium
- Published
- Jul 17, 2026
- Updated
- Jul 17, 2026
- Reserved
- May 18, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 6.5 Medium | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | GitHub_M |
Weaknesses
- CWE-674 Uncontrolled Recursion
Affected Products
| Product | Versions |
|---|---|
python-zeroconfpython-zeroconf |
|
References
- https://github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-9pgc-3ccv-5297
- https://github.com/python-zeroconf/python-zeroconf/pull/1719
- https://github.com/python-zeroconf/python-zeroconf/commit/f9e23592137f30fdf7ef710dba065da31c79b1cf
- https://github.com/python-zeroconf/python-zeroconf/releases/tag/0.149.5
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