CVE-2026-47183: zeroconf Unbounded Exception-dedup State Retains Packet Vulnerability
MODERATECVE-2026-47183 is a MODERATE (CVSS 6.5) unbounded exception-dedup state retains packet vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting zeroconf libraries in the PyPI ecosystem. The issue involves unbounded exception-dedup state retains packet buffers via traceback frame locals, enabling lan-local memory exhaustion. Remediation is available by upgrading affected packages to version 0.149.6.
CVE-2026-47183 at a Glance
Security Impact
CVSS: 6.5
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
How to Fix CVE-2026-47183
To remediate this vulnerability, upgrade all affected zeroconf dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
pip install zeroconf>=0.149.6Run the following command in your project directory to verify that all resolved dependencies use the patched release:
pip show zeroconfHow to Check if You Are Affected
To determine whether your Python environment is affected by CVE-2026-47183, inspect your installed packages using pip:
pip show zeroconfAnalyze the terminal output to locate any version of zeroconf in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.149.6), your application is affected.
Note: The pip show zeroconf command checks currently installed packages in your active Python environment.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. In zeroconf, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-47183 Affected zeroconf Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
zeroconf
|
PyPI |
< 0.149.6
|
0.149.6
|
References
Frequently Asked Questions
What is CVE-2026-47183?
Which zeroconf versions are affected?
What version fixes CVE-2026-47183?
Is zeroconf affected?
What is the CVSS score of CVE-2026-47183?
What CWE is associated with CVE-2026-47183?
How can I check PyPI dependencies for CVE-2026-47183?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-phvx-9mgw-67r5",
"modified" : "2026-05-29T20:13:08Z",
"published" : "2026-05-29T20:13:08Z",
"aliases" : [ "CVE-2026-47183" ],
"summary" : "zeroconf: Unbounded exception-dedup state retains packet buffers via traceback frame locals, enabling LAN-local memory exhaustion",
"details" : "### Impact\n`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.\n\nAny 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.\n\n### Patches\nFixed in `zeroconf` 0.149.6 ([PR #1717](https://github.com/python-zeroconf/python-zeroconf/pull/1717)). Upgrade to `>= 0.149.6`.\n\n### Workarounds\nThere 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.\n\n### Resources\n- [PR #1717](https://github.com/python-zeroconf/python-zeroconf/pull/1717), fix\n- [Issue #1714](https://github.com/python-zeroconf/python-zeroconf/issues/1714), public tracking issue\n- [RFC 6762 §17](https://www.rfc-editor.org/rfc/rfc6762#section-17), [RFC 6762 §18](https://www.rfc-editor.org/rfc/rfc6762#section-18), [CWE-400](https://cwe.mitre.org/data/definitions/400.html)",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "PyPI",
"name" : "zeroconf"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "0.149.6"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/python-zeroconf/python-zeroconf/security/advisories/GHSA-phvx-9mgw-67r5"
}, {
"type" : "WEB",
"url" : "https://github.com/python-zeroconf/python-zeroconf/issues/1714"
}, {
"type" : "WEB",
"url" : "https://github.com/python-zeroconf/python-zeroconf/pull/1717"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/python-zeroconf/python-zeroconf"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-400" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2026-05-29T20:13:08Z",
"nvd_published_at" : null
}
}