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Vulnerability · Published Jul 17, 2026 · Assigned by GitHub_M

CVE-2026-47180Zeroconf: Unbounded recursion in DNS compression-pointer decoder allows LAN-local denial of service

Medium 6.5

In plain English

A medium-severity security flaw in python-zeroconf from python-zeroconf. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.4%top 68.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12python-zeroconfno fix listedDEBIAN-CVE-2026-47180
Debian:13python-zeroconfno fix listedDEBIAN-CVE-2026-47180
Debian:14python-zeroconf0.149.6-1DEBIAN-CVE-2026-47180
PyPIzeroconf0.149.5GHSA-9pgc-3ccv-5297
PyPIzeroconf0.149.5PYSEC-2026-3436
Ubuntu:22.04:LTSpython-zeroconfno fix listedUBUNTU-CVE-2026-47180
Ubuntu:24.04:LTSpython-zeroconfno fix listedUBUNTU-CVE-2026-47180
Ubuntu:26.04:LTSpython-zeroconfno fix listedUBUNTU-CVE-2026-47180

Affected products (as reported)

VendorProductVersions
python-zeroconf python-zeroconf < 0.149.5

Weakness: CWE-674 · Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References