For something like a PDF, macOS would open Preview, or some other PDF-handling app, to handle it if the user opens it in the Finder. So the PDF would have to h

For something like a PDF, macOS would open Preview, or some other PDF-handling app, to handle it if the user opens it in the Finder. So the PDF would have to have code in it that exploited some security weakness in the associated app that would cause the code to be executed, correct? Just trying to make sure I'm understanding.