FUXA is a web-based Process Visualization (SCADA/HMI/Dashboard) software. Version 1.3.0 has an unauthenticated Remote Code Execution vulnerability when "secureEnabled" is set to "true". The "POST /api/runscript" endpoint checks authorization against the stored script's permission by ID, but when "test: true" is set in the request, it compiles and executes attacker-supplied code instead of the stored script's code. An unauthenticated attacker who knows a valid script ID and name may execute arbitrary code via test mode if at least one server-side script exists and is accessible without restrictive permissions. Script IDs and names can be obtained through the unauthenticated information disclosure in "GET /api/project" (reported separately). The only prerequisite is that at least one server-side script exists in the project. Version 1.3.1 fixes the issue.