Bug 2501843 (CVE-2026-47183)

Summary:	CVE-2026-47183 zeroconf: Zeroconf: Denial of Service via unbounded memory growth from mDNS messages
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	eglynn, jjoyce, jpretori, jschluet, lhh, mburns, mgarciac
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in zeroconf, a Python implementation of multicast DNS (mDNS) service discovery. An unauthenticated attacker on the local network can send specially crafted mDNS messages, causing the system to store an unbounded number of error messages. This can lead to excessive memory consumption, resulting in a denial of service (DoS) where mDNS-dependent features degrade or the process terminates unexpectedly.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2508070
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Description OSIDB Bzimport 2026-07-17 19:01:56 UTC

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.