CVE-2026-47184 python-zeroconf CVE debrief

Who should care

Users of Zeroconf, particularly those using versions prior to 0.149.7, should be aware of this vulnerability and take steps to mitigate it. This includes updating to version 0.149.7 or later, and monitoring for potential memory exhaustion and performance issues. Affected operator, platform, vulnerability-management, and security-team impact may occur if not addressed.

Technical summary

The vulnerability in Zeroconf allows unauthenticated hosts on the local link to cause memory exhaustion and performance issues by multicasting valid mDNS responses with unique names. This is due to the DNSCache._async_add function inserting every response record into cache, _expirations, _expire_heap, and service_cache without a cap. The issue is fixed in version 0.149.7. Affected product deployments may experience slower cache lookups, slower async_expire passes, and broken discovery, registration, and ServiceBrowser callbacks. Defensive impact includes prioritizing updates to version 0.149.7 or later, and monitoring for potential issues.

Defensive priority

Medium

Recommended defensive actions

• Update Zeroconf to version 0.149.7 or later
• Monitor for potential memory exhaustion and performance issues
• Implement rate limiting on mDNS responses
• Verify cache and expiration settings
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The vulnerability is described in the CVE record and the NVD detail page. The fix is available in version 0.149.7 of Zeroconf. Evidence limits suggest that affected deployments may exist in managed environments, particularly those using versions prior to 0.149.7. Defenders should verify cache and expiration settings, and monitor for potential memory exhaustion and performance issues. Limited source detail indicates that further review of compensating controls and vendor guidance is necessary.

Official resources