What is CVE-2026-33356?

CVE-2026-33356 is a high-severity vulnerability in Meari Iot Cloud Mqtt Broker Emqx, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 7.7/10. Published 2026-05-11.

How severe is CVE-2026-33356?

High severity. CVSS v3 base score is 7.7 out of 10.

Auth bypass in Meari Iot Cloud Mqtt Broker Emqx

CVE-2026-33356

In Meari IoT Cloud MQTT Broker deployments running EMQX 4.x, any authenticated low-privilege account can subscribe to global wildcard topics and receive telemetry from devices the user does not own. The broker enforces publish restrictions but does not enforce equivalent subscribe authorization at per-device scope.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published 2026-05-11 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.7 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.004 (26.5th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 27th percentile — 26.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001

Affected products

Meari Iot Cloud Mqtt Broker Emqx — versions 4.x

Weakness classification (CWE)

CWE-639 — Authorization Bypass Through User-Controlled Key

References

44488dab-36db-4358-99f9-bc116477f914 (technical-description)
44488dab-36db-4358-99f9-bc116477f914 (third-party-advisory)

Frequently asked questions

What is CVE-2026-33356?: CVE-2026-33356 is a high-severity vulnerability in Meari Iot Cloud Mqtt Broker Emqx, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 7.7/10. Published 2026-05-11.
How severe is CVE-2026-33356?: High severity. CVSS v3 base score is 7.7 out of 10.