CVE-2026-33217
NATS allows MQTT clients to bypass ACL checks
- State
- Published
- Severity
- 7.1 High
- Published
- Mar 25, 2026
- Updated
- Sep 9, 2026
- Reserved
- Mar 17, 2026
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 | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 7.1 High | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N | GitHub_M |
| 3.1 | 8.1 High | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N | redhat-SADP |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
nats-servernats-io |
|
References
- https://github.com/nats-io/nats-server/security/advisories/GHSA-jxxm-27vp-c3m5
- https://advisories.nats.io/CVE/secnote-2026-07.txt
- https://access.redhat.com/security/cve/CVE-2026-33217vdb-entry
- RHBZ#2451446issue-tracking
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33217.json
- https://access.redhat.com/errata/RHSA-2026:22347vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:23345vendor-advisory
- https://access.redhat.com/errata/RHSA-2026:21769vendor-advisory
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