CVE-2026-25228 is a medium-severity path traversal vulnerability in signalk-server (npm), affecting versions <= 2.20.2. It is fixed in 2.20.3.
Summary 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. Details Platform: Windows (Linux only allows traversal up a single directory) Authentication Required: Yes (ability to write depends on user's permission) The vulnerability exists in the validateAppId() function within the applicationData API handler. This function validates the appid parameter but only checks for forward slashes: Root Cause: The validation only blocks / characters On Windows, path.join() uses the platform's native path separator Windows treats both / and \ as valid directory separators Backslash-based traversal sequences like ..\..\.. pass validation When path.join() processes these on Windows, each .. traverses up one directory level PoC Reproduction Steps: Set up SignalK Server on a Windows machine Obtain a valid device or user authentication token Run the PoC script: bash python3 pocwindowsappidtraversal.py --target http://[signalK server IP]:3000 --token <YOURTOKEN> Recommended Fix Short-term: Add backslash validation to validateAppId(): javascript function validateAppId(appid) { if (appid.includes('/') || appid.includes('\') || appid.length >= 30) { return false; } return true; } Use path.normalize() and validate that resolved paths remain within the intended directory: javascript const resolvedPath = path.normalize(path.join(baseDir, appid)); if (!resolvedPath.startsWith(path.normalize(baseDir))) { throw new Error('Invalid path'); }
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
CVE-2026-25228 has a CVSS score of 5.0 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
A fixed version is available (2.20.3). Upgrading removes the vulnerable code path.
npm
signalk-server (<= 2.20.2)signalk-server → 2.20.3 (npm)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter instead of chasing every advisory.
Kodem's runtime-powered SCA identifies whether CVE-2026-25228 is reachable in your applications. Explore open-source security for your team.
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Upgrade signalk-server to 2.20.3 or later to resolve this vulnerability.
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-25228 is a medium-severity path traversal vulnerability in signalk-server (npm), affecting versions <= 2.20.2. It is fixed in 2.20.3. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
CVE-2026-25228 has a CVSS score of 5.0 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
signalk-server (npm) versions <= 2.20.2 is affected.
Yes. CVE-2026-25228 is fixed in 2.20.3. Upgrade to this version or later.
Whether CVE-2026-25228 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade signalk-server to 2.20.3 or later.