Description
NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, when no_auth_user was configured, a parser fast path intended for ordinary client connections could also apply to route or leafnode listeners, allowing an unauthenticated peer to bypass inter-server CONNECT authentication and operate with the privileges associated with that connection type. This issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| nats-io | nats-server | < 2.11.16, >= 2.12.0-preview.1, < 2.12.6 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | nats-server | 2.14.1-1 | — |
| Debian 13 | nats-server | No fix yet | — |
| Debian 12 | nats-server | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 25.10 | nats-server | No fix yet | — |
| Ubuntu 24.04 LTS | nats-server | No fix yet | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 26.04 LTS | nats-server | No fix yet | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | telegraf | 1.31.0-27 | — |
Advisories 1
- WID-SEC-2026-2132 NATS Server: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jul 14, 2026
References
- https://github.com/nats-io/nats-server/security/advisories/GHSA-38x3-76xf-cq45
- https://github.com/nats-io/nats-server/commit/7b81dd455ea95960090a84858c7662827948d1b6
- https://github.com/nats-io/nats-server/commit/8b8e1ad4ceed32321e00d4fc6e76be05bc13bca6
- https://github.com/nats-io/nats-server/commit/b86147e81710a52b72a7f7275f91d69f723f5cb3
- https://github.com/nats-io/nats-server/releases/tag/v2.11.16
- https://github.com/nats-io/nats-server/releases/tag/v2.12.7
- https://github.com/nats-io/nats-server/releases/tag/v2.14.0