What’s Vulnerable › Vulnerabilities

CVE-2026-41893: Signal K Server's WebSocket Login Endpoint Lacks Rate Limiting (Credential Brute-Force)

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-05-09 · updated 2026-07-24
• Weakness: CWE-307

Description

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-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-vmfm-ch9h-5c7g
• https://github.com/SignalK/signalk-server/security/advisories/GHSA-vmfm-ch9h-5c7g

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