NATS allows MQTT clients to bypass ACL checks
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.
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describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-33217US | medium6.5OT elevated | — | ||
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 ACL… | ||||
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references
External citations — patches, advisories, analysis.
- https://access.redhat.com/errata/RHSA-2026:21769WEB
- https://access.redhat.com/errata/RHSA-2026:22347WEB
- https://access.redhat.com/errata/RHSA-2026:23345WEB
- https://access.redhat.com/security/cve/CVE-2026-33217WEB
- https://advisories.nats.io/CVE/secnote-2026-07.txtADVISORY
- https://bugzilla.redhat.com/show_bug.cgi?id=2451446WEB
- https://github.com/nats-io/nats-server/security/advisories/GHSA-jxxm-27vp-c3m5ADVISORY
- https://nvd.nist.gov/vuln/detail/CVE-2026-33217WEB
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