CVE-2026-40076: OpenMRS Module Upload Vulnerable to Path Traversal (Zip Slip)

The endpoint POST /openmrs/ws/rest/v1/module is vulnerable to a path traversal (Zip Slip) attack. An authenticated attacker can upload a crafted .omod archive containing ZIP entries with directory traversal sequences. Upon automatic extraction by the server, the incomplete path validation in WebModuleUtil.startModule() fails to prevent entries such as web/module/../../../../malicious.jsp from being written outside the intended module directory. If the traversal target falls within the web application root (e.g., /usr/local/tomcat/webapps/openmrs/), the attacker achieves arbitrary file write and subsequent Remote Code Execution.

Notably, other extraction methods in the same codebase (ModuleUtil.expandJar(), TestInstallUtil.addZippedTestModules()) are properly protected with normalize().startsWith() checks — this vulnerability is an oversight where the same fix was not applied.

Furthermore, the module.allow_web_admin runtime property, which is intended to restrict administrators from managing modules via the web interface, only gates the Legacy UI controller entry point. The REST API endpoint POST /openmrs/ws/rest/v1/module does not check this property, allowing this restriction to be fully bypassed.