nats-io/nats-server · Security
NATS allows MQTT clients to bypass ACL checks
- GHSA ID
- GHSA-jxxm-27vp-c3m5
- CVE ID
- CVE-2026-33217
- Severity
- high
- Published
- Updated
- CVSS
- 7.1 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
- CVSS v3
- 7.1 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
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
When using ACLs on message subjects, these ACLs were not applied in the $MQTT.> namespace, allowing MQTT clients to bypass ACL checks for MQTT subjects.
Affected Versions
Any version before v2.12.6 or v2.11.15
Workarounds
None.
CWEs
- CWE-863 · Incorrect Authorization