CVE-2026-33215

About vulnerability

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

Affected product:

Grafana , Loki , MinIO , benmathews/bench , centrifugal/centrifuge , github.com/benmathews/bench , github.com/centrifugal/centrifuge , github.com/go-kit/kit , github.com/grpc-ecosystem/go-grpc-middleware , github.com/hashicorp/raft-wal , github.com/influxdata/telegraf , github.com/nats-io/nats-server , github.com/nats-io/nats-streaming-server , github.com/prometheus/client_golang , github.com/prometheus/common , go-kit/kit , grafana/tempo , grpc-ecosystem/go-grpc-middleware , hashicorp/raft-wal , heroku/x , influxdata/telegraf , nats-io/nats-server , nats-io/nats-streaming-server , prometheus/client_golang , prometheus/common , spf13/cobra , spf13/viper

Affected packages:

github.com/nats-io/nats-server @ 2.1.4 (+39 more)