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Vulnerability · Published Jul 17, 2026 · Assigned by GitHub_M

CVE-2026-48045Zeroconf: Unbounded TC-deferred queue allows LAN-local memory exhaustion via spoofed-source flood

Medium 6.5

In plain English

A medium-severity resource allocation without limits 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 0.149.12, AsyncListener.handle_query_or_defer retained every truncated TC-bit incoming query, each up to _MAX_MSG_ABSOLUTE = 8966 bytes, in self._deferred[addr] and armed a per-address timer in self._timers[addr] without capping the per-address list or distinct addr keys, allowing unauthenticated hosts on the local link over UDP/5353 (224.0.0.251 / ff02::fb) to spoof sources, grow _deferred and _timers, and cause memory exhaustion and quadratic CPU burn. This issue is fixed in version 0.149.12.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12python-zeroconfno fix listedDEBIAN-CVE-2026-48045
Debian:13python-zeroconfno fix listedDEBIAN-CVE-2026-48045
Debian:14python-zeroconf0.149.16-1DEBIAN-CVE-2026-48045
PyPIzeroconf0.149.12GHSA-9663-mqmp-p9mm
PyPIzeroconf0.149.12PYSEC-2026-3435
Ubuntu:22.04:LTSpython-zeroconfno fix listedUBUNTU-CVE-2026-48045
Ubuntu:24.04:LTSpython-zeroconfno fix listedUBUNTU-CVE-2026-48045
Ubuntu:26.04:LTSpython-zeroconfno fix listedUBUNTU-CVE-2026-48045

Affected products (as reported)

VendorProductVersions
python-zeroconf python-zeroconf < 0.149.12

Weakness: CWE-770 · Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References