CVE-2026-33950

Signal K Server before version 2.19.0 contains two vulnerabilities that can be chained to steal JWT tokens without any authentication. The first is unauthenticated WebSocket request enumeration via the serverevents=all parameter, and the second is unauthenticated polling of access request status, which returns the JWT token in plaintext after an administrator approves the request.

Signal K Server before version 2.19.0 allows an unauthenticated attacker to pollute the internal state (restoreFilePath) via the /skServer/validateBackup endpoint, enabling hijacking of the administrator's Restore functionality to overwrite critical configuration files, leading to account takeover and RCE.

Signal K Server prior to 2.28.0 has a vulnerability in makeRemoteRequest() that accepts attacker-controlled host, port, useTLS, and selfsignedcert parameters without validating the destination. When security is not configured, the endpoints testSignalKConnection, requestAccess, and checkAccessRequest are accessible without authentication, allowing port scanning, exfiltration of cloud metadata and internal service data, and lateral movement.

Signal K Server prior to version 2.25.0 protects HTTP login endpoints (POST /login and POST /signalk/v1/auth/login) with express-rate-limit (default: 100 attempts per 10-minute window). However, the WebSocket login path — sending {login: {username, password}} messages over an established WebSocket connection — calls app.securityStrategy.login() directly without any rate limiting. An attacker can bypass HTTP rate limiting entirely by opening a WebSocket connection and attempting unlimited password guesses at the speed bcrypt allows (~20 attempts/sec with 10 salt rounds). This issue has been fixed in version 2.25.0.

Signal K Server before version 2.24.0 has a prototype read vulnerability via `from` field bypass. A low-privileged authenticated user can bypass prototype boundary filtering to read internal functions and properties from the global prototype object.

Signal K Server before version 2.24.0 has a vulnerability in OIDC login/logout handlers where the unvalidated Host header is used to construct the OAuth2 redirect_uri. Since redirectUri is unset by default, an attacker can spoof the Host header to steal OAuth authorization codes and hijack user sessions.

Signal K Server before version 2.24.0-beta.1 exposes an unauthenticated HTTP endpoint PUT /signalk/v1/api/sourcePriorities that allows remote attackers to modify navigation data source priorities. Changes are applied immediately and persisted.

Signal K Server before version 2.19.0 has a vulnerability in the access request system that combines two related issues: improper display of the `permissions` field (less visible than the description) and unconditional trust in the `X-Forwarded-For` header for determining the client's IP address. An attacker can exploit these flaws to craft a convincing social engineering attack against an administrator, impersonating a trusted device and requesting elevated permissions.

Signal K Server prior to version 2.19.0 in the appstore interface allows administrators to install npm packages through a REST API endpoint. While the package name is validated, the version parameter accepts arbitrary npm version specifiers including URLs, enabling installation from attacker-controlled sources and execution of malicious postinstall scripts. Version 2.19.0 contains a patch.

Signal K Server prior to version 2.19.0 has an unauthenticated information disclosure vulnerability allowing any user to retrieve sensitive system information, including the full SignalK data schema, connected serial devices, and installed analyzer tools. Version 2.19.0 patches the issue.