GHSA-vprv-35vv-q339
NATS has pre-auth server panic via leafnode handling
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| Go | github.com/nats-io/nats-server/v2 | < 2.11.15 | 2.11.15 |
| Go | github.com/nats-io/nats-server/v2 | >= 2.12.0-RC.1, < 2.12.6 | 2.12.6 |
| Go | github.com/nats-io/nats-server | all versions | no fix listed |
Details
As written in the advisory (Markdown source, shown as plain text).
### 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>
References
External links from the advisory. They lead to third-party sites.