NATS allows MQTT clients to bypass ACL checks
### Background NATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing. The nats-server provides an MQTT client interface. ### Problem Description 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. ### Affected Versions Any version before v2.12.6 or v2.11.15 ### Workarounds None.
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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.
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