GitHub Advisoryadvisory · Go

GHSA-jxxm-27vp-c3m5 NATS allows MQTT clients to bypass ACL checks

HIGH Published 2026-03-24 Modified 2026-03-27 Official page ↗
Aliases
CVE-2026-33217
Ecosystem
Go
Packages
github.com/nats-io/nats-server/v2, github.com/nats-io/nats-server
Severity
High
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
Weaknesses
CWE-863
Reviewed
2026-03-24

Affected packages

• Go github.com/nats-io/nats-server/v2: < 2.11.15 → fixed in 2.11.15 • Go github.com/nats-io/nats-server/v2: >= 2.12.0-RC.1, < 2.12.6 → fixed in 2.12.6 • Go github.com/nats-io/nats-server: all versions (no fix yet)

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 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.

Related

Alias · CVE (1)

  • CVE-2026-33217 NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. vulnerability

Weakness · CWE (1)

  • CWE-863 Incorrect Authorization weakness

References