SignalK signalk-server up to 2.20.2 on Windows validateAppId path traversal

Summaryinfo

A vulnerability classified as critical was found in SignalK signalk-server up to 2.20.2 on Windows. This affects the function validateAppId. Such manipulation leads to path traversal. This vulnerability is listed as CVE-2026-25228. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in SignalK signalk-server up to 2.20.2 on Windows and classified as critical. Affected by this issue is the function validateAppId. The manipulation with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Impacted is confidentiality. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-25228 since 01/30/2026. The exploitation is known to be easy. The attack may be launched remotely. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1006.

Upgrading to version 2.20.3 eliminates this vulnerability. Applying the patch 9bcf61c8fe2cb8a40998b913a02fb64dff9e86c7 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-5343). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• SignalK

Name

• signalk-server

Version

• 2.20.0
• 2.20.1
• 2.20.2

License

• open-source

Website

• Product: https://github.com/SignalK/signalk-server/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Once again VulDB remains the best source for vulnerability data.

Discussion