CVE-2026-41893: Signalk Signal K Server

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

Signal K Server is a server application that runs on a central hub in a boat. Prior to version 2.25.0, the HTTP login endpoints (POST /login and POST /signalk/v1/auth/login) are protected by express-rate-limit (default: 100 attempts per 10-minute window, configurable via HTTP_RATE_LIMITS). 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 patched in version 2.25.0.

Affected products

• Signalk Signal K Server: before 2.25.0 (fixed in 2.25.0)

Published 2026-05-09. Last modified 2026-07-24.