Improper authorization control for web services In github.com/nats-io/nats-server/v2
Description
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
Mitigation
Update Impact
Minimal update. May introduce new vulnerabilities or breaking changes.
Ecosystem | Package | Affected version | Patched versions |
|---|---|---|---|
 go | github.com/nats-io/nats-server/v2 | 2.11.15, 2.12.6 |
Aliases