CVE-2026-47183 zeroconf: Unbounded exception-dedup state retains packet buffers via traceback frame locals, enabling LAN-local memory exhaustion
Unauthenticated local network attackers can exhaust memory in the zeroconf library by sending crafted mDNS packets, causing service degradation or crashes.
- 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-2026-47183?
CVE-2026-47183 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 0.149.6, DNSIncoming._log_exception_debug and the four QuietLogger exception-dedup methods stored an unbounded _seen_logs dictionary keyed by attacker-influenced IncomingDecodeError messages, retaining sys.exc_info() tracebacks whose frame locals kept raw packet self.data buffers and allowing unauthenticated hosts on the local link over UDP/5353 (224.0.0.251 / ff02::fb) to drive memory growth until mDNS-dependent features degrade or the process is OOM-killed. This issue is fixed in version 0.149.6.
Weakness: CWE-400
Which versions are affected by CVE-2026-47183?
3 open source packages ship an affected version, including zeroconf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
zeroconf PyPI | All versions | 0.149.6 |
zeroconf PyPI | All versions | 0.149.6 |
zeroconf PyPI | All versions | 0.149.6 |
Products include Paulsm Zeroconf.
How do I fix CVE-2026-47183?
Upgrade zeroconf to 0.149.6 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-2026-47183 being exploited?
There is no known exploitation of CVE-2026-47183 in the wild and no public exploit code.
Other vulnerabilities in python-zeroconf
- CVE-2026-47180 Zeroconf: Unbounded recursion in DNS compression-pointer decoder allows LAN-local denial of service
- 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-2026-47183, GHSA-phvx-9mgw-67r5, PYSEC-2026-3437, UBUNTU-CVE-2026-47183.