TI-2025-40835 Aliases CVE-2025-66398 GHSA-w3x5-7c4c-66p9

Signal K Server has Unauthenticated State Pollution leading to Remote Code Execution (RCE)

HIGH 82CWE-78Published 2026-01-01 · Updated 2026-01-05

Key facts

Attack vector: Network
Privileges required: None
User interaction: Required
Attack complexity: Low
Impact type: Code execution
Confidentiality · integrity · availability: High · High · High
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-78.

Summary

Signal K Server is a server application that runs on a central hub in a boat. Prior to version 2.19.0, an unauthenticated attacker can pollute the internal state (`restoreFilePath`) of the server via the `/skServer/validateBackup` endpoint. This allows the attacker to hijack the administrator's "Restore" functionality to overwrite critical server configuration files (e.g., `security.json`, `package.json`), leading to account takeover and Remote Code Execution (RCE). Version 2.19.0 patches this vulnerability.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.1985 97th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed signalk-server (SignalK): 2.19.0signalk-server (npm): 2.19.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
SignalK	signalk-server	before 2.19.0	2.19.0	Patch available	CNA
—	signalk-server (npm)	before 2.19.0	2.19.0	Patch available	GHSA-w3x5-7c4c-66p9

signalk-server VendorSignalK Affected before 2.19.0 Fixed in 2.19.0 Patch available CNA
signalk-server (npm) Vendor— Affected before 2.19.0 Fixed in 2.19.0 Patch available GHSA-w3x5-7c4c-66p9

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:signalk:signal_k_server::::::::	before 2.19.0	Vulnerable	SignalK

cpe:2.3:a:signalk:signal_k_server:*:*:*:*:*:*:*:* Versions before 2.19.0 Vulnerable ·SignalK

Remediation

Fix · CNA signalk-server (SignalK) Fixed in 2.19.0
Fix · GHSA-w3x5-7c4c-66p9 signalk-server (npm) Fixed in 2.19.0 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2025-66398
2026-10-03 Alias added: GHSA-w3x5-7c4c-66p9

References

Exploit 1

https://github.com/SignalK/signalk-server/security/advisories/GHSA-w3x5-7c4c-66p9

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2025-66398

Other 3

TI-2026-26300 signalk-server: Privilege Escalation by Admin Role Injection via /enableSecurity CVSS 3.1CRITICAL 9.4
TI-2025-42138 Signal K Server vulnerable to JWT Token Theft via WebSocket Enumeration and Unauthenticated Polling CVSS 3.1CRITICAL 9.1
TI-2026-30295 Signal K Server's WebSocket Login Endpoint Lacks Rate Limiting (Credential Brute-Force) CVSS 4.0HIGH 8.7
TI-2025-42657 Signal K Server Vulnerable to Access Request Spoofing CVSS 3.1HIGH 8.8
TI-2026-18939 RCE - Command Injection in Signal K set-system-time plugin CVSS 3.1CRITICAL 10.0
TI-2025-42137 Signal K Server Vulnerable to Remote Code Execution via Malicious npm Package CVSS 4.0HIGH 7.3

See all 13 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences