What’s Vulnerable › Vulnerabilities

CVE-2026-39320: Signal K Server has an Unauthenticated Regular Expression Denial of Service (ReDoS) via WebSocket Subscription Paths

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-04-21 · updated 2026-10-26
• Weakness: CWE-400

Description

Signal K Server is a server application that runs on a central hub in a boat. Versions prior to 2.25.0 are vulnerable to an unauthenticated Regular Expression Denial of Service (ReDoS) attack within the WebSocket subscription handling logic. By injecting unescaped regex metacharacters into the `context` parameter of a stream subscription, an attacker can force the server's Node.js event loop into a catastrophic backtracking loop when evaluating long string identifiers (like the server's self UUID). This results in a total Denial of Service (DoS) where the server CPU spikes to 100% and becomes completely unresponsive to further API or socket requests. Version 2.25.0 contains a fix.

Affected products

• signalk-server: before 2.25.0 — fixed in 2.25.0

How to fix

Upgrade to a fixed version: signalk-server 2.25.0. Check the vendor advisory for mitigations.

References

• https://github.com/SignalK/signalk-server/commit/215d81eb700d5419c3396a0fbf23f2e246dfac2d
• https://github.com/SignalK/signalk-server/pull/2568
• https://github.com/SignalK/signalk-server/releases/tag/v2.25.0
• https://github.com/SignalK/signalk-server/security/advisories/GHSA-7gcj-phff-2884
• https://github.com/SignalK/signalk-server/security/advisories/GHSA-7gcj-phff-2884

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