Domoticz is a free, open source home automation system for Linux, Windows, macOS, and Raspberry Pi. Prior to 2026.3, the "udevices" JSON command handler, "Cmd_UpdateDevices" in "main/WebServerCmds.cpp", performed no "session.rights" check before invoking a Lua parser script, while its sibling command handlers gate access by role. A low-privilege authenticated user could trigger execution of an existing operator-installed Lua parser script with attacker-controlled input through the "GET /json.htm" endpoint with "type=command" and "param=udevices". The "script" parameter also lacked a ".." path-traversal guard: "CLuaHandler::executeLuaScript" in "main/LuaHandler.cpp" constructed the filename from the parser directory and the supplied script name before passing it to "luaL_loadfile". Execution is limited to already-installed valid Lua files; this is not arbitrary code execution, and the advisory states that file-write and upload paths require administrator privileges. This issue is addressed in version 2026.3.