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Fencer Vulns
medium 6.5

CVE-2026-47180 json

Zeroconf: Unbounded recursion in DNS compression-pointer decoder allows LAN-local denial of service

published 2026-05-29 5 mo ago modified 2026-08-17 2 mo ago also GHSA-9pgc-3ccv-5297 , PYSEC-2026-3436 , EUVD-2026-45247

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

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.

Patch / fix

  • pypi zeroconf 0.149.5
  • paulsm zeroconf 0.149.5
  • python-zeroconf Debian 14 0.149.6-1

debian advisories DEBIAN-CVE-2026-47180

  • python-zeroconf openSUSE Leap 16.0 0.136.0-bp160.2.1

opensuse advisories openSUSE-SU-2026:21175-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-47180 updated cvss 6.5

zeroconf: Zeroconf: Denial of Service via crafted mDNS packets

  • Red Hat OpenShift Container Platform 4 python-zeroconf, python3-zeroconf
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenStack Platform 16.2 python3-zeroconf Red Hat OpenStack Platform 17.1 python3-zeroconf
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat OpenStack Platform 18.0 python-zeroconf
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 6.5 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 6.5 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi zeroconf
<0.149.5
0.149.5

Affected products

  • python-zeroconf python-zeroconf

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.