CVE
CVE-2026-33217
NATS allows MQTT clients to bypass ACL checks
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.
Package Versions Affected
Package Version
patch Availability
No items found.
Automatically patch vulnerabilities without upgrading
Fix Without Upgrading
Detect compatible fix
Apply safe remediation
Fix with a single pull request
CVSS Version
Severity
Base Score
CVSS Version
Score Vector
C
H
U
7.1
-
3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
C
H
U
0
-
3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
C
H
U
7.1
-
3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
Related Resources
No items found.
References
https://github.com/nats-io/nats-server/security/advisories/GHSA-jxxm-27vp-c3m5, https://nvd.nist.gov/vuln/detail/CVE-2026-33217, https://advisories.nats.io/CVE/secnote-2026-07.txt, https://github.com/nats-io/nats-server
Basic Information
Ecosystem
