CVE-2026-33217
NATS allows MQTT clients to bypass ACL checks
7.1
HIGH
CVSS 3.1
EPSS 0.04%
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.
How to fix CVE-2026-33217
To remediate CVE-2026-33217, upgrade the affected package to a fixed version below.
- —upgrade to 2.11.15 or later
- —no fix listed
- —no fix listed
- —no fix listed
- —upgrade to 2.11.15 or later
- —upgrade to 2.11.15 or later
Is CVE-2026-33217 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (6)
- from 0, < 2.11.15, >= 2.12.0, < 2.12.6
- from 0
- from 0
- from 0
- from 0, < 2.11.15
- from 0, < 2.11.15, >= 2.12.0-RC.1, < 2.12.6
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.1 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N |