Generate PDF using Contact Form 7 < 4.2.2 - Unauthenticated Server-Side Request Forgery via Array-Valued Form Field

The Generate PDF using Contact Form 7 WordPress plugin before 4.2.2 does not restrict the destination of the image fetch its PDF renderer performs on submitted form content, allowing unauthenticated users to make the server request internal resources and read the response back through the generated PDF.