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CVE-2026-33217

NATS allows MQTT clients to bypass ACL checks

Published: Mar 25, 2026Updated: Mar 26, 2026 Sources: CVE List NVDCWE-863
NVD MITRE
7.1CVSSHIGH
EPSS Score
0.2%
Top 95.3%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:UC:LI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:LConfidentiality
Low
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-863

Affected Products

nats-servernats-io
On-prem
Databases / cache-message-queue
nats-serverlinuxfoundation
Mixed
AI / ML / ml-framework
nats-iooss-projectDatabases
linuxfoundationoss-projectUSAI / MLaka yocto, pytorch, everest

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Initial Access
View detailed technique mapping

References

https://github.com/nats-io/nats-server/security/advisories/GHSA-jxxm-27vp-c3m5
github.com
https://advisories.nats.io/CVE/secnote-2026-07.txt
advisories.nats.io

Timeline

Published
Mar 25, 2026
Last Updated
Mar 26, 2026

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