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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| python-zeroconf | python-zeroconf | < 0.149.16 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | python-zeroconf | 0.149.16-1 | — |
| Debian 13 | python-zeroconf | No fix yet | — |
| Debian 12 | python-zeroconf | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | python-zeroconf | No fix yet | — |
| Ubuntu 24.04 LTS | python-zeroconf | No fix yet | — |
| Ubuntu 22.04 LTS | python-zeroconf | No fix yet | — |
| Ubuntu 20.04 LTS | python-zeroconf | No fix yet | — |
| Ubuntu 18.04 LTS | python-zeroconf | No fix yet | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | python-zeroconf | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-zeroconf | 0.149.16-1.1 | openSUSE-SU-2026:11036-1 |
| openSUSE Leap 16.0 | python-zeroconf | 0.136.0-bp160.2.1 | openSUSE-SU-2026:21175-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | zeroconf | < 0.149.16 | 0.149.16 | GHSA-qc2x-6f54-m6h9 |
Advisories 2
- openSUSE-SU-2026:21175-1 Security update for python-zeroconf SUSE / openSUSE Security Updates · Jul 2, 2026
- openSUSE-SU-2026:11036-1 python311-zeroconf-0.149.16-1.1 on GA media SUSE / openSUSE Security Updates · Jun 16, 2026
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