What’s Vulnerable › Vulnerabilities

CVE-2026-47183: Zeroconf: Unbounded exception-dedup state retains packet buffers via traceback frame locals, enabling LAN-local memory exhaustion

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-17 · updated 2026-08-17
• Weakness: CWE-400

Description

Zeroconf is a pure Python implementation of multicast DNS service discovery. Prior to 0.149.6, DNSIncoming._log_exception_debug and the four QuietLogger exception-dedup methods stored an unbounded _seen_logs dictionary keyed by attacker-influenced IncomingDecodeError messages, retaining sys.exc_info() tracebacks whose frame locals kept raw packet self.data buffers and allowing unauthenticated hosts on the local link over UDP/5353 (224.0.0.251 / ff02::fb) to drive memory growth until mDNS-dependent features degrade or the process is OOM-killed. This issue is fixed in version 0.149.6.

Affected products

• python-zeroconf: before 0.149.6 — fixed in 0.149.6

How to fix

Upgrade to a fixed version: python-zeroconf 0.149.6. Check the vendor advisory for mitigations.

References

• https://github.com/python-zeroconf/python-zeroconf/commit/95561e28b24922358f1991e38e3a86d70d72dcec
• https://github.com/python-zeroconf/python-zeroconf/issues/1714
• https://github.com/python-zeroconf/python-zeroconf/pull/1717
• https://github.com/python-zeroconf/python-zeroconf/releases/tag/0.149.6
• https://github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-phvx-9mgw-67r5

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