CVE-2026-48045 Zeroconf: Unbounded TC-deferred queue allows LAN-local memory exhaustion via spoofed-source flood
Unauthenticated local attackers can cause memory exhaustion and CPU burn in the Zeroconf library by flooding spoofed truncated queries.
- 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-2026-48045?
CVE-2026-48045 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 0.149.12, AsyncListener.handle_query_or_defer retained every truncated TC-bit incoming query, each up to _MAX_MSG_ABSOLUTE = 8966 bytes, in self._deferred[addr] and armed a per-address timer in self._timers[addr] without capping the per-address list or distinct addr keys, allowing unauthenticated hosts on the local link over UDP/5353 (224.0.0.251 / ff02::fb) to spoof sources, grow _deferred and _timers, and cause memory exhaustion and quadratic CPU burn. This issue is fixed in version 0.149.12.
Weakness: CWE-770
Which versions are affected by CVE-2026-48045?
3 open source packages ship an affected version, including zeroconf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
zeroconf PyPI | All versions | 0.149.12 |
zeroconf PyPI | All versions | 0.149.12 |
zeroconf PyPI | All versions | 0.149.12 |
Products include Paulsm Zeroconf.
How do I fix CVE-2026-48045?
Upgrade zeroconf to 0.149.12 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-2026-48045 being exploited?
There is no known exploitation of CVE-2026-48045 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-2026-47183 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-2026-48487 Zeroconf: Unvalidated rdlength in record payload readers allows LAN-local cache corruption via crafted mDNS packet
Sources
Also known as DEBIAN-CVE-2026-48045, GHSA-9663-mqmp-p9mm, PYSEC-2026-3435, UBUNTU-CVE-2026-48045.