Signal K Server is a server application that runs on a central hub in a boat. Versions prior to 2.19.0 expose two features that can be chained together to steal JWT authentication tokens without any prior authentication. The attack combines WebSocket-based request enumeration with unauthenticated polling of access request status. The first is Unauthenticated WebSocket Request Enumeration: When a WebSocket client connects to the SignalK stream endpoint with the `serverevents=all` query parameter, the server sends all cached server events including `ACCESS_REQUEST` events that contain details about pending access requests. The `startServerEvents` function iterates over `app.lastServerEvents` and writes each cached event to any connected client without verifying authorization level. Since WebSocket connections are allowed for readonly users (which includes unauthenticated users when `allow_readonly` is true), attackers receive these events containing request IDs, client identifiers, descriptions, requested permissions, and IP addresses. The second is Unauthenticated Token Polling: The access request status endpoint at `/signalk/v1/access/requests/:id` returns the full state of an access request without requiring authentication. When an administrator approves a request, the response includes the issued JWT token in plaintext. The `queryRequest` function returns the complete request object including the token field, and the REST endpoint uses readonly authentication, allowing una…

Affected: npm: signalk-server

SignalK Server exposes two features that can be chained together to steal JWT authentication tokens without any prior authentication. The attack combines WebSocket-based request enumeration with unauthenticated polling of access request status.

**Unauthenticated WebSocket Request Enumeration**: When a WebSocket client connects to the SignalK stream endpoint with the `serverevents=all` query parameter, the server sends all cached server events including `ACCESS_REQUEST` events that contain details about pending access requests. The `startServerEvents` function iterates over `app.lastServerEvents` and writes each cached event to any connected client without verifying authorization level. Since WebSocket connections are allowed for readonly users (which includes unauthenticated users when `allow_readonly` is true), attackers receive these events containing request IDs, client identifiers, descriptions, requested permissions, and IP addresses.

**Unauthenticated Token Polling**: The access request status endpoint at `/signalk/v1/access/requests/:id` returns the full state of an access request without requiring authentication. When an administrator approves a request, the response includes the issued JWT token in plaintext. The `queryRequest` function returns the complete request object including the token field, and the REST endpoint uses readonly authentication, allowing unauthenticated access.

An attacker has two paths to exploit these vulnerabilities:

1. The attacker creat…