LAN-local denial of service via pointer-chain recursion
Published Jul 17, 2026 · Updated Jul 17, 2026
Uncontrolled recursion in python-zeroconf before 0.149.5 allows attackers to degrade mDNS services via crafted local-link packets. DNSIncoming._decode_labels_at_offset follows each unique compression pointer recursively without bounding chain depth, and RecursionError escapes packet initialization. Any unauthenticated host sharing the Layer 2 network can trigger sustained CPU use and log flooding that degrades mDNS-dependent features while packets are replayed.
Summary
What happened
Uncontrolled recursion in python-zeroconf before 0.149.5 allows attackers to degrade mDNS services via crafted local-link packets. DNSIncoming._decode_labels_at_offset follows each unique compression pointer recursively without bounding chain depth, and RecursionError escapes packet initialization. Any unauthenticated host sharing the Layer 2 network can trigger sustained CPU use and log flooding that degrades mDNS-dependent features while packets are replayed.
The record
- CVE
- CVE-2026-47180
- Published
- Jul 17, 2026
- Updated
- Jul 17, 2026
- Vendor
- python-zeroconf
- Product
- python-zeroconf
- Classifications
- CWE-674, T1499.004
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 17, 2026CVE publishedPublication date reported by the CVE source.
- Jul 17, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.149.5
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream compression-pointer chain regression reproducerproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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