nats-io/nats-server · Security
NATS is vulnerable to MQTT hijacking via Client ID
- GHSA ID
- GHSA-fcjp-h8cc-6879
- CVE ID
- CVE-2026-33215
- Severity
- medium
- Published
- Updated
- CVSS
- 6.5 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:L
- CVSS v3
- 6.5 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:L
Description
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
CWEs
- CWE-287 · Improper Authentication