CVE-2026-48487
Zeroconf: Unvalidated rdlength in record payload readers allows LAN-local cache corruption via crafted mDNS packet
- State
- Published
- Severity
- 5.3 Medium
- Published
- Jul 17, 2026
- Updated
- Jul 20, 2026
- Reserved
- May 21, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 5.3 Medium | 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 | GitHub_M |
Weaknesses
- CWE-130 Improper Handling of Length Parameter Inconsistency
Affected Products
| Product | Versions |
|---|---|
python-zeroconfpython-zeroconf |
|
References
- https://github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-qc2x-6f54-m6h9
- https://github.com/python-zeroconf/python-zeroconf/issues/1752
- https://github.com/python-zeroconf/python-zeroconf/pull/1756
- https://github.com/python-zeroconf/python-zeroconf/commit/544449596e645fcaad3834fa0cb614a54f847a82
- https://github.com/python-zeroconf/python-zeroconf/releases/tag/0.149.16
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