Summary
zeroconf: Unbounded exception-dedup state retains packet buffers via traceback frame locals, enabling LAN-local memory exhaustion
Workarounds
There is no in-process workaround; upgrading is the fix. Otherwise, restrict mDNS (UDP/5353) to trusted Layer-2 segments via AP client isolation, guest-network separation, or host firewall rules.
Resources
- PR #1717, fix
- Issue #1714, public tracking issue
- RFC 6762 §17, RFC 6762 §18, CWE-400
Impact
DNSIncoming._log_exception_debug and the four QuietLogger exception-dedup methods stored an unbounded _seen_logs dict keyed by str(sys.exc_info()[1]). The seven IncomingDecodeError messages raised from _read_name / _decode_labels_at_offset (RFC 6762 §18 name-decoding error paths) all embed self.source, the peer's ephemeral source port, varying per packet, plus byte offset and pointer link, so every attacker-influenced combination produced a fresh dedup key. The stored value was the full sys.exc_info() triple, whose traceback's frame locals retained self.data (the raw inbound packet, up to 8966 bytes per RFC 6762 §17). Each unique malformed packet therefore pinned ~9 KB until process exit.
Any unauthenticated host on the local link (UDP/5353, 224.0.0.251 / ff02::fb) can drive memory growth at line rate; that includes a guest on the same Wi-Fi, a compromised IoT device, or a container on a shared bridge. On memory-constrained deployments (Home Assistant on Raspberry-Pi-class hardware is the canonical victim) sustained traffic trivially OOM-kills the process, and mDNS-dependent features (HomeKit, Chromecast/Matter, AirPlay, printers) degrade or fail.
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
CVE-2026-47183 has a CVSS score of 6.5 (Medium). The vector is reachable from an adjacent network, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.149.6); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Fixed in zeroconf 0.149.6 (PR #1717). Upgrade to >= 0.149.6.
Frequently Asked Questions
- What is CVE-2026-47183? CVE-2026-47183 is a medium-severity uncontrolled resource consumption vulnerability in zeroconf (pip), affecting versions < 0.149.6. It is fixed in 0.149.6. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
- How severe is CVE-2026-47183? CVE-2026-47183 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of zeroconf are affected by CVE-2026-47183? zeroconf (pip) versions < 0.149.6 is affected.
- Is there a fix for CVE-2026-47183? Yes. CVE-2026-47183 is fixed in 0.149.6. Upgrade to this version or later.
- Is CVE-2026-47183 exploitable, and should I be worried? Whether CVE-2026-47183 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-47183 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-47183? Upgrade
zeroconfto 0.149.6 or later.