Signal K Server vulnerable to JWT Token Theft via WebSocket Enumeration and Unauthenticated Polling

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS

• CVE-2025-68620: 0.54% estimated exploitation activity in the next 30 days; percentile 45.45 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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 ACCESSREQUEST 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 allowreadonly is true), attackers receive these events containing request IDs, client identifiers, descriptions, requested permissions, and IP addresses. Unauthenticated Token Polling: The access request status…

Published by the source

2 Jan 2026, 15:28 UTC

Last modified by the source

3 Feb 2026, 03:14 UTC

Source last checked

26 Oct 2026, 12:41 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-fq56-hvg6-wvm5

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-fq56-hvg6-wvm5

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-fq56-hvg6-wvm5

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2025-68620

Advisory: Signal K Server vulnerable to JWT Token Theft via WebSocket Enumeration and Unauthenticated Polling
IDs: CVE-2025-68620, GHSA-fq56-hvg6-wvm5
Record: https://patchnext.com/advisories/cve-2025-68620 (revision 3, source checked 26 Oct 2026, 12:41 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: signalk-server 2.19.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm signalk-server: affected < 2.19.0; fixed in 2.19.0

## Suggested inspection (read-only)
- `npm ls signalk-server --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on signalk-server.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-fq56-hvg6-wvm5 (GitHub-reviewed advisory GHSA-fq56-hvg6-wvm5 lists affected ranges: npm signalk-server >=0 <2.19.0)
- Verified: https://osv.dev/vulnerability/GHSA-fq56-hvg6-wvm5 (OSV record GHSA-fq56-hvg6-wvm5 lists affected ranges: npm signalk-server >=0 <2.19.0 (fixed))

Commands are suggestions: review each one before running it.