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Fencer Vulns
medium 5.3

CVE-2026-48487 json

Zeroconf: Unvalidated rdlength in record payload readers allows LAN-local cache corruption via crafted mDNS packet

published 2026-06-22 4 mo ago modified 2026-08-17 2 mo ago also GHSA-qc2x-6f54-m6h9 , PYSEC-2026-3438 , EUVD-2026-45252

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits
0
none known

Summary

Zeroconf is a pure Python implementation of multicast DNS service discovery. Prior to 0.149.16, _read_character_string and _read_string in src/zeroconf/_protocol/incoming.py advanced self.offset by attacker-declared RDLENGTH without checking it against self._data_len, allowing unauthenticated hosts on the local link over UDP/5353 (224.0.0.251 / ff02::fb) to send a TXT, HINFO, or A/AAAA record with rdlength=65535 and seed DNSCache and ServiceInfo.properties with truncated, attacker-shaped key/value or address records. This issue is fixed in version 0.149.16.

Patch / fix

  • pypi zeroconf 0.149.16
  • paulsm zeroconf 0.149.16
  • python-zeroconf Debian 14 0.149.16-1

debian advisories DEBIAN-CVE-2026-48487

  • python-zeroconf openSUSE Leap 16.0 0.136.0-bp160.2.1
  • python-zeroconf openSUSE Tumbleweed 0.149.16-1.1

opensuse advisories openSUSE-SU-2026:21175-1openSUSE-SU-2026:11036-1

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-2026-48487 updated cvss 4.3

zeroconf: Zeroconf: Data integrity vulnerability via malformed DNS records

  • 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

0.47% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 5.3 CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CNA 4.0 5.3 CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
GitHub 3.1 6.5 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
OSV 3.1 6.5 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
pypi zeroconf
<0.149.16
0.149.16

Affected products

  • python-zeroconf python-zeroconf

Classification

Weakness
  • CWE-130 Improper Handling of Length Parameter Inconsistency

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.