Medium [CVE-2026-47180] Denial of Service via crafted mDNS packets
This medium-severity Red Hat Linux advisory covers CVE-2026-47180 affecting Red Hat OpenShift Container Platform 4, Red Hat OpenStack Platform 16.2, Red Hat OpenStack Platform 17.1.
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Summary
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. This can trigger a recursion error, leading to sustained CPU usage, excessive logging, and degraded mDNS services, ultimately causing a Denial of Service.
Exploitation requires the attacker to be on the same local link as the affected host, consistent with Red Hat's Adjacent (AV:A) attack vector scoring. Red Hat's CVSS score matches the vendor/CVE.org assessment for this flaw.
This flaw is one of a batch of related Zeroconf issues discovered and fixed close together (CVE-2026-47180, CVE-2026-47183, CVE-2026-47184, CVE-2026-48045, CVE-2026-48487); all affect the same Red Hat product streams in the same way and were triaged consistently as a batch. Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
Weakness: CWE-835.
- < 0.149.5
- < 224.0.0.251
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
- 0.149.5
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
Mitigation checklist
- Upgrade to zeroconf 0.149.5 or later once packaged in the affected Red Hat product. Where upgrading isn't immediately possible, restricting the affected host's exposure to the local network segment (network segmentation or firewalling multicast DNS traffic on UDP/5353) reduces the practical attack surface, since exploitation requires local-link access.
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
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