High · published March 26, 2026
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.2.0 and prior to versions 2.11.14 and 2.12.5, a missing sanity check on a WebSockets frame could trigger a server panic in the nats-server. This happens before authentication, and so is exposed to anyone who can connect to the websockets port. Versions 2.11.14 and 2.12.5 contains a fix. A workaround is available. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-points. If one is able to do so, a defense in depth of restricting either of these will mitigate the attack.
| Product | Versions | Fixed in |
|---|---|---|
| linuxfoundation/nats-server | ≥ 2.2.0, < 2.11.14 | 2.11.14 |
| linuxfoundation/nats-server | ≥ 2.12.0, < 2.12.5 | 2.12.5 |