# Signal K Server buffered logs exposure in unauthenticated WebSocket

Source: https://junglewise.ai/threats/signal-k-server-buffered-logs-exposed-to-unauthenticated-websocket-b7032aad  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-12. Updated: 2026-11-12  
License: CC BY 4.0 with a link back

Severity: medium · CVSS 5.3 · Published 2026-11-12

Signal K Server is a real-time data platform used in marine systems to distribute vessel data over WebSocket connections. An unauthenticated attacker can connect before login and subscribe to the server log path to receive sensitive buffered logs, exposing operational details, configuration information, and potentially credentials without any authentication required.

Technologies: [signalk-server (npm)](https://junglewise.ai/threats/technologies/signalk-server), [Signal K Server](https://junglewise.ai/threats/technologies/signal-k-server). Vendors: [npm](https://junglewise.ai/threats/vendors/npm), [Signal K](https://junglewise.ai/threats/vendors/signal-k).

## Quick answers

**Is This vulnerability exploited in the wild?** No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.

**How severe is This vulnerability?** Medium severity, with a CVSS score of 5.3, published 12 November 2026.

**Which products and versions are affected?** signalk-server (npm) < 2.31.0-beta.1, SEMVER:introduced=0,fixed=2.31.0-beta.1; Signal K Server before 2.31.0-beta.1.

**Is there a fix for This vulnerability?** Yes. signalk-server (npm): upgrade to 2.31.0-beta.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is This vulnerability attacked?** It is attacked over the network, in a hosted service.

**Am I affected?** Check whether you run signalk-server (npm) or Signal K Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- signalk-server (npm): upgrade to 2.31.0-beta.1 or later

  ```sh
  npm install signalk-server@2.31.0-beta.1
  ```


## Technical details

The vulnerability exists in the WebSocket subscription handler which intentionally allows unauthenticated connections to support login over WebSocket, but fails to apply access control to log path subscriptions. The `processSubscribe` function handles log subscriptions separately from normal subscriptions, bypassing the `securityStrategy.filterReadDelta` access control check that applies to all other paths. An attacker can subscribe to the log path to receive the entire buffered server log replay without authentication.

## Affected products

- Signal K Server before 2.31.0-beta.1

## Timeline

- 2026-11-12: disclosed

## Related threats

- [Signal K Server path traversal in REST resources endpoint](https://junglewise.ai/threats/cve-2026-123807-signal-k-server-is-a-server-application-that-runs-on-a-central)
- [Signal K resources API path traversal and RCE](https://junglewise.ai/threats/signal-k-resources-api-path-traversal-can-disclose-the-jwt-signing-0c6398ee)
- [Signal K Server missing authentication in log download](https://junglewise.ai/threats/cve-2026-118690-signal-k-server-before-2-33-0-contains-a-missing-authentication)
- [Signal K Server SSRF in App Store icon fetcher](https://junglewise.ai/threats/cve-2026-115752-signal-k-server-from-2-28-0-beta-2-before-2-34-0-contains-a)
- [Signal K Server SSRF in remote connection endpoints](https://junglewise.ai/threats/cve-2026-55591-signal-k-server-ssrf-in-remote-connection-endpoints)