High 7.1Published Mar 25, 2026

CVE-2026-33217NATS allows MQTT clients to bypass ACL checks

Updated under an hour ago (Oct 26, 2026, 7:30 PM ET)

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It affects nats-io nats-server and 3 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for nats-io nats-server

Exploited in the last 30 days

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.

CVSS: 7.1 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
Weakness (CWE): CWE-863, CWE-425
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Modified
Record last updated: Sep 9, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

nats-io nats-server nats_io:nats_server (from the name)	before 2.11.15; from 2.12.0-RC.1, < 2.12.6	CNA record
Red Hat Multicluster Global Hub 1.4.5 redhat:multicluster_globalhub	from 1779579439 not affected	CISA ADP
Red Hat Red Hat OpenShift Container Platform 4 redhat:openshift	4	CISA ADP
linuxfoundation nats-server linuxfoundation:nats-server	before 2.11.15; from 2.12.0 before 2.12.6	NVD

References

References

https://github.com/nats-io/nats-server/security/advisories/GHSA-jxxm-27vp-c3m5	x-refsource-confirm, vendor-advisory
https://advisories.nats.io/CVE/secnote-2026-07.txt	x-refsource-misc, vendor-advisory
https://access.redhat.com/errata/RHSA-2026:21769
https://access.redhat.com/errata/RHSA-2026:22347
https://access.redhat.com/errata/RHSA-2026:23345
https://access.redhat.com/security/cve/CVE-2026-33217
https://bugzilla.redhat.com/show_bug.cgi?id=2451446
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33217.json

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.