Vulnerability in Paulsm Zeroconf
CVE-2026-48487
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.005 (39.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Paulsm Zeroconf
- Python-Zeroconf — versions < 0.149.16
Weakness classification (CWE)
References
- github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-qc2x-6f54-m… (Vendor Advisory)
- github.com/python-zeroconf/python-zeroconf/issues/1752 (Patch, Issue Tracking)
- github.com/python-zeroconf/python-zeroconf/pull/1756 (Patch, Issue Tracking)
- github.com/python-zeroconf/python-zeroconf/commit/544449596e645fcaad3834fa0cb61… (Patch)
- github.com/python-zeroconf/python-zeroconf/releases/tag/0.149.16 (Release Notes)
Frequently asked questions
- What is CVE-2026-48487?
- CVE-2026-48487 is a medium-severity vulnerability in Paulsm Zeroconf, classified under Improper Handling of Length Parameter Inconsistency. CVSS score: 5.3/10. Published 2026-07-17.
- How severe is CVE-2026-48487?
- Medium severity. CVSS v3 base score is 5.3 out of 10.