CVE-2026-33217

HIGH

NATS allows MQTT clients to bypass ACL checks

Title source: cna
STIX 2.1

Description

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, 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. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.

Scores

CVSS v3 7.1
EPSS 0.0003
EPSS Percentile 8.9%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-863
Status published
Products (5)
linuxfoundation/nats-server < 2.11.15
nats-io/nats-server 0Go
nats-io/nats-server 0 - 2.11.15Go
nats-io/nats-server < 2.11.15
nats-io/nats-server >= 2.12.0-RC.1, < 2.12.6
Published Mar 25, 2026
Tracked Since Mar 26, 2026