CVE-2026-33216 HIGH

CVE-2026-33216: NATS has MQTT plaintext password disclosure

Vendor Nats-Io
Product nats-server
Weakness CWE-256
Published March 25, 2026
Last update June 30, 2026

CVSS base score

8.6/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality High
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

What the vulnerability does

01Description

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, for MQTT deployments using usercodes/passwords: MQTT passwords are incorrectly classified as a non-authenticating identity statement (JWT) and exposed via monitoring endpoints. Versions 2.11.14 and 2.12.6 contain a fix. As a workaround, ensure monitoring end-points are adequately secured. Best practice remains to not expose the monitoring endpoint to the Internet or other untrusted network users.

Key dates

02Disclosure timeline

March 25, 2026 CVE published
June 30, 2026 Record updated