NATS is vulnerable to MQTT hijacking via Client ID
### 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 Sessions and Messages can by hijacked via MQTT Client ID malfeasance. ### Affected Versions Any version before v2.12.6 or v2.11.15 ### Workarounds None. ### Resources * This document is canonically: <https://advisories.nats.io/CVE/secnote-2026-06.txt> * GHSA advisory: <https://github.com/nats-io/nats-server/security/advisories/GHSA-fcjp-h8cc-6879> * MITRE CVE entry: <https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-33215>
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-33215US | medium6.5 | — | ||
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server provides an MQTT client interface. Prior to versions 2.11.15 and 2.1… | ||||
references
External citations — patches, advisories, analysis.
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