Signalk: >> Signal K Server Security Vulnerabilities
Signal K Server is a server application that runs on a central hub in a boat. Versions prior to 2.19.0 of the appstore interface allow administrators to install npm packages through a REST API endpoint. While the endpoint validates that the package name exists in the npm registry as a known plugin or webapp, the version parameter accepts arbitrary npm version specifiers including URLs. npm supports installing packages from git repositories, GitHub shorthand syntax, and HTTP/HTTPS URLs pointing to tarballs. When npm installs a package, it can automatically execute any `postinstall` script defined in `package.json`, enabling arbitrary code execution. The vulnerability exists because npm's version specifier syntax is extremely flexible, and the SignalK code passes the version parameter directly to npm without sanitization. An attacker with admin access can install a package from an attacker-controlled source containing a malicious `postinstall` script. Version 2.19.0 contains a patch for the issue.
CVSS Score
7.3
EPSS Score
0.006
Published
2026-01-01
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 unauthenticated access. An attacker has two paths to exploit these vulnerabilities. Either the attacker creates their own access request (using the IP spoofing vulnerability to craft a convincing spoofed request), then polls their own request ID until an administrator approves it, receiving the JWT token; or the attacker passively monitors the WebSocket stream to discover request IDs from legitimate devices, then polls those IDs and steals the JWT tokens when administrators approve them, hijacking legitimate device credentials. Both paths require zero authentication and enable complete authentication bypass. Version 2.19.0 fixes the underlying issues.
CVSS Score
9.1
EPSS Score
0.005
Published
2026-01-01
Signal K Server is a server application that runs on a central hub in a boat. Prior to version 2.19.0, an unauthenticated attacker can pollute the internal state (`restoreFilePath`) of the server via the `/skServer/validateBackup` endpoint. This allows the attacker to hijack the administrator's "Restore" functionality to overwrite critical server configuration files (e.g., `security.json`, `package.json`), leading to account takeover and Remote Code Execution (RCE). Version 2.19.0 patches this vulnerability.
CVSS Score
9.6
EPSS Score
0.179
Published
2026-01-01
Signal K Server is a server application that runs on a central hub in a boat. A Denial of Service (DoS) vulnerability in versions prior to 2.19.0 allows an unauthenticated attacker to crash the SignalK Server by flooding the access request endpoint (`/signalk/v1/access/requests`). This causes a "JavaScript heap out of memory" error due to unbounded in-memory storage of request objects. Version 2.19.0 fixes the issue.
CVSS Score
7.5
EPSS Score
0.005
Published
2026-01-01
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