CVE-2025-68620 Signal K Server vulnerable to JWT Token Theft via WebSocket Enumeration and Unauthenticated Polling

What is CVE-2025-68620?

CVE-2025-68620 is a critical authentication bypass vulnerability in signalk-server, published on 1 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Weakness: CWE-288

Which versions are affected by CVE-2025-68620?

2 open source packages ship an affected version, including signalk-server. It affects 1 product.

Products include Signalk Signal K Server.

How do I fix CVE-2025-68620?

Upgrade signalk-server to 2.19.0 or later.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2025-68620 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-68620 exists.

Other vulnerabilities in signalk-server

• CVE-2026-23515 RCE - Command Injection in Signal K set-system-time plugin Critical 10.0
• CVE-2025-66398 Signal K Server has Unauthenticated State Pollution leading to Remote Code Execution (RCE) Critical 9.7
• CVE-2026-33950 signalk-server: Privilege Escalation by Admin Role Injection via /enableSecurity Critical 9.4
• CVE-2026-41893 Signal K Server's WebSocket Login Endpoint Lacks Rate Limiting (Credential Brute-Force) High 8.7
• CVE-2026-39320 Signal K Server has an Unauthenticated Regular Expression Denial of Service (ReDoS) via WebSocket Subscription Paths High 7.5

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-fq56-hvg6-wvm5.