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MQTT plaintext password disclosure

High
philpennock published GHSA-v722-jcv5-w7mc Mar 24, 2026

Package

gomod github.com/nats-io/nats-server/v2 (Go)

Affected versions

<= 2.12.5, <= 2.11.14

Patched versions

2.12.6, 2.11.15

Description

Background

NATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing.

The nats-server provides an MQTT client interface.

Problem Description

For MQTT deployments using usercodes/passwords: MQTT passwords are incorrectly classified as a non-authenticating identity statement (JWT) and exposed via monitoring endpoints.

Affected Versions

Any version before v2.12.6 or v2.11.15

Workarounds

Ensure your monitoring end-points are adequately secured.

Best practice remains to not expose the monitoring endpoint to the Internet or other untrusted network users.

References

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

CVE ID

CVE-2026-33216

Weaknesses

No CWEs
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