Bug 2501850 (CVE-2026-47180)

Summary: CVE-2026-47180 zeroconf: Zeroconf: Denial of Service via crafted mDNS packets
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: eglynn, jjoyce, jpretori, jschluet, lhh, mburns, mgarciac
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Zeroconf, a Python implementation of multicast DNS service discovery. An unauthenticated attacker on the local network can send a specially crafted multicast DNS (mDNS) packet with chained pointers. This can trigger a recursion error, leading to sustained CPU usage, excessive logging, and degraded mDNS services, ultimately causing a Denial of Service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2508069    
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Description OSIDB Bzimport 2026-07-17 19:02:21 UTC
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.