CVE-2026-33217
NATS allows MQTT clients to bypass ACL checks
CVSS Score
7.1
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-863 |
| Vendor | nats-io |
| Product | nats-server |
| Published | Mar 25, 2026 |
| Last Updated | Jul 20, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
High
Availability
None
Affected Versions
nats-io / nats-server
< 2.11.15 >= 2.12.0-RC.1, < 2.12.6
References
github.com: https://github.com/nats-io/nats-server/security/advisories/GHSA-jxxm-27vp-c3m5 advisories.nats.io: https://advisories.nats.io/CVE/secnote-2026-07.txt access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-33217 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2451446 security.access.redhat.com: https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33217.json access.redhat.com: https://access.redhat.com/errata/RHSA-2026:22347 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:23345 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:21769