Description
NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, a WebSocket listener could route requests for the MQTT-over-WebSocket path into MQTT handling even when MQTT was not configured, allowing an unauthenticated client with access to the WebSocket listener to reach uninitialized MQTT state and crash the server process. This issue is fixed in versions 2.14.3 and 2.12.12.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| nats-io | nats-server | >= 2.14.0-RC.1, < 2.14.3, < 2.12.12 | — |
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 | 2.14.3-1 | — |
| Debian 13 | nats-server | No fix yet | — |
| Debian 12 | nats-server | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | nats-server | No fix yet | — |
| 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-p957-7v2w-g93g
- https://github.com/nats-io/nats-server/commit/73b3dd9a5ea0fa7bf08b702338676355b29b5fb4
- https://github.com/nats-io/nats-server/commit/837536b98b3a9280b993282155ff2bdd3ca38c30
- https://github.com/nats-io/nats-server/releases/tag/v2.12.12
- https://github.com/nats-io/nats-server/releases/tag/v2.14.3