Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| python-zeroconf | python-zeroconf | < 0.149.5 | — |
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 | 0.149.6-1 | — |
| 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 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 | < 0.149.5 | 0.149.5 | GHSA-9pgc-3ccv-5297 |
Advisories 1
- openSUSE-SU-2026:21175-1 Security update for python-zeroconf SUSE / openSUSE Security Updates · Jul 2, 2026
References
- https://github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-9pgc-3ccv-5297
- https://github.com/python-zeroconf/python-zeroconf/pull/1719
- https://github.com/python-zeroconf/python-zeroconf/commit/f9e23592137f30fdf7ef710dba065da31c79b1cf
- https://github.com/python-zeroconf/python-zeroconf/releases/tag/0.149.5