Overview
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 allows hub/spoke topologies using “leafnode” connections by other nats-servers.
Problem Description
A client which can connect to the leafnode port can crash the nats-server with a certain malformed message pre-authentication.
Affected Versions
Any version before v2.12.6 or v2.11.15
Workarounds
- Disable leafnode support if not needed.
- Restrict network connections to your leafnode port, if plausible without compromising the service offered.
References
- This document is canonically: https://advisories.nats.io/CVE/secnote-2026-10.txt
- GHSA advisory: https://github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339
- MITRE CVE entry: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-33218
Details
- 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)