CVE-2026-47180 Zeroconf: Unbounded recursion in DNS compression-pointer decoder allows LAN-local denial of service
An attacker on the local network can cause a denial of service in the Zeroconf library by sending crafted mDNS packets that trigger unbounded recursion.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-47180?
CVE-2026-47180 is a medium-severity denial of service vulnerability in python-zeroconf, published on 17 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-674
Which versions are affected by CVE-2026-47180?
3 open source packages ship an affected version, including zeroconf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
zeroconf PyPI | All versions | 0.149.5 |
zeroconf PyPI | All versions | 0.149.5 |
zeroconf PyPI | All versions | 0.149.5 |
Products include Paulsm Zeroconf.
How do I fix CVE-2026-47180?
Upgrade zeroconf to 0.149.5 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-47180 being exploited?
There is no known exploitation of CVE-2026-47180 in the wild and no public exploit code.
Other vulnerabilities in python-zeroconf
- CVE-2026-47183 zeroconf: Unbounded exception-dedup state retains packet buffers via traceback frame locals, enabling LAN-local memory exhaustion
- CVE-2026-47184 Zeroconf: Unbounded DNS record cache allows LAN-local memory exhaustion via multicast flood
- CVE-2026-48045 Zeroconf: Unbounded TC-deferred queue allows LAN-local memory exhaustion via spoofed-source flood
- CVE-2026-48487 Zeroconf: Unvalidated rdlength in record payload readers allows LAN-local cache corruption via crafted mDNS packet
Sources
Also known as DEBIAN-CVE-2026-47180, GHSA-9pgc-3ccv-5297, PYSEC-2026-3436, UBUNTU-CVE-2026-47180.