NATS has MQTT plaintext password disclosure
### 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 monitoring end-points are adequately secured. Best practice remains to not expose the monitoring endpoint to the Internet or other untrusted network users.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-33216US | high7.5 | — | ||
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… | ||||
references
External citations — patches, advisories, analysis.
- https://advisories.nats.io/CVE/secnote-2026-05.txtWEB
- https://github.com/nats-io/nats-serverPACKAGE
- https://github.com/nats-io/nats-server/commit/b5b63cfc35a57075e09c1f57503d31721bed8099WEB
- https://github.com/nats-io/nats-server/security/advisories/GHSA-v722-jcv5-w7mcWEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-33216ADVISORY
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