CVE-2026-25228: Signalk Signal K Server

Medium severity, CVSS 4.3. EPSS: 0.4% 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 2.20.3, a path traversal vulnerability in SignalK Server's applicationData API allows authenticated users on Windows systems to read, write, and list arbitrary files and directories on the filesystem. The validateAppId() function blocks forward slashes (/) but not backslashes (\), which are treated as directory separators by path.join() on Windows. This enables attackers to escape the intended applicationData directory. This vulnerability is fixed in 2.20.3.

Affected products

• Signalk Signal K Server: before 2.20.3 (fixed in 2.20.3)

Published 2026-02-02. Last modified 2026-06-17.