Description
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 2.12.5, Sessions and Messages can by hijacked via MQTT Client ID malfeasance. Versions 2.11.15 and 2.12.5 patch the issue. No known workarounds are available.
Problem types
CWE-287: Improper Authentication
CWE-488: Exposure of Data Element to Wrong Session
Product status
>= 2.12.0-RC.1, < 2.12.6
References
github.com/...server/security/advisories/GHSA-fcjp-h8cc-6879
advisories.nats.io/CVE/secnote-2026-06.tx