MyScreenTools version 2.2.1.0 contains a critical OS command injection vulnerability in its GIF compression tool. The vulnerability arises because the application does not properly sanitize user-supplied file paths before passing them to the Windows command shell (cmd.exe). This flaw exists in the CMD() function within the GIFSicleTool\Form_gif_sicle_tool.cs source file, which constructs shell commands by concatenating unsanitized input and executing them. An attacker can exploit this to execute arbitrary system commands with the privileges of the user running the application.