CVE-2026-33356
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceIn Meari IoT Cloud MQTT Broker deployments running EMQX 4.x, authenticated low-privilege users can subscribe to global wildcard topics (e.g., device/# or +/telemetry) and receive telemetry from devices they do not own. The broker properly enforces publish authorization per device but lacks equivalent subscribe authorization controls, allowing unauthorized cross-user data access.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify EMQX versionCheck the running EMQX version by querying the management API at /api/v4/status or running 'emqx version' in the broker shellAffected if The installed version is EMQX 4.x (any minor version within the 4.x line)
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Confirm Meari IoT Cloud Broker deploymentReview system documentation or deployment configuration to confirm this is a Meari IoT Cloud MQTT Broker environment using EMQX 4.x as the underlying brokerAffected if The deployment is a Meari IoT Cloud MQTT Broker using EMQX 4.x
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Review EMQX authorization configurationInspect the EMQX authorization settings via the dashboard under 'Authorization' or by examining the emqx.conf file for authorization sources and rulesAffected if Authorization rules exist for publish actions but lack equivalent subscribe-specific rules, or no subscribe authorization is defined
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Check wildcard subscription permissionsTest subscribing to a wildcard topic such as device/# or +/telemetry using a low-privilege authenticated user account that does not own those devicesAffected if The subscription succeeds and receives messages from devices owned by other users
You are affected if running a Meari IoT Cloud MQTT Broker on EMQX 4.x where low-privilege users can successfully subscribe to wildcard topics and receive telemetry data from devices they do not own.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataImplement per-device subscribe authorization in EMQX 4.x by configuring authorization rules that restrict topic subscriptions to only those owned by the authenticated user, mirroring existing publish restrictions. Alternatively, restrict wildcard topic subscriptions to administrator-level accounts only.
- Consultation6.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-33356 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-33356 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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