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CVE-2026-41893 SignalK CVE debrief

CVE-2026-41893 affects Signal K Server versions before 2.25.0. The HTTP login endpoints are rate-limited, but the WebSocket login path accepts username/password messages without the same protection, allowing repeated guessing at the pace of bcrypt verification. The issue was addressed in version 2.25.0.

Vendor
SignalK
Product
signalk-server
CVSS
HIGH 8.7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-09
Original CVE updated
2026-07-24
Advisory published
2026-05-09
Advisory updated
2026-07-24

Who should care

Operators and maintainers of Signal K Server installations, especially any deployment exposing the login-capable WebSocket interface to untrusted networks.

Technical summary

The source description says POST /login and POST /signalk/v1/auth/login are protected by express-rate-limit, with a default of 100 attempts per 10 minutes and configurable limits via HTTP_RATE_LIMITS. In contrast, the WebSocket login flow that sends {login: {username, password}} messages invokes app.securityStrategy.login() directly and does not apply rate limiting. That creates an authentication abuse path consistent with CWE-307 (excessive authentication attempts): an attacker can bypass the HTTP controls and continue password guessing over an established WebSocket connection. The patch is included in Signal K Server v2.25.0.

Defensive priority

High. This is an online authentication weakness that can materially increase password-guessing risk against exposed deployments.

Recommended defensive actions

  • Upgrade Signal K Server to version 2.25.0 or later.
  • Verify that WebSocket-based authentication follows the same rate-limiting and lockout policy as HTTP login endpoints.
  • Review HTTP_RATE_LIMITS and confirm the configured limits match your deployment risk tolerance.
  • Monitor authentication failures and repeated WebSocket login attempts for suspicious patterns.
  • If immediate upgrading is not possible, reduce exposure of login-capable interfaces to trusted networks only.

Evidence notes

The debrief is based on the CVE description and the official GitHub references listed by NVD. The description explicitly states that HTTP login endpoints are rate-limited while the WebSocket login path is not, and that version 2.25.0 contains the fix. NVD also lists CWE-307 and references the commit, pull request, release tag, and GitHub Security Advisory for corroboration. Timing context uses the CVE published/modified timestamp of 2026-05-09T20:16:27.273Z.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-41893 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-41893

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-41893 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-41893

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.