GHSA-vprv-35vv-q339
NATS has pre-auth server panic via leafnode handling
At a glance
- Published
- Updated
- CVE
- CVE-2026-33218
- Aliases
- BIT-nats-2026-33218, GO-2026-4837
- CVSS_V3
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 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 1. Disable leafnode support if not needed. 2. 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>
Affected packages
| Package | Versions |
|---|---|
| Go · github.com/nats-io/nats-server/v2 | introduced 0, fixed 2.11.15 |
| Go · github.com/nats-io/nats-server/v2 | introduced 2.12.0-RC.1, fixed 2.12.6 |
| Go · github.com/nats-io/nats-server | introduced 0 |
References
- https://github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339 WEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-33218 ADVISORY
- https://advisories.nats.io/CVE/secnote-2026-10.txt WEB
- https://github.com/nats-io/nats-server PACKAGE
Sources
| Source | Licence |
|---|---|
| OSV.dev | CC-BY 4.0 — GitHub Advisory Database |