medium6.5
CVE-2026-47180
zeroconf has unbounded recursion in DNS compression-pointer decoder that allows LAN-local denial of service
Impact
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 packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | zeroconf | < 0.149.5 | 0.149.5 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Paulsm | Zeroconf | before 0.149.5 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-9pgc-3ccv-5297
- https://github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-9pgc-3ccv-5297
- https://github.com/python-zeroconf/python-zeroconf/issues/1713
- 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