[Chilinot]

PDFs can do all sorts of shenanigans, such as bundle executable javascript that runs when the file is opened.

[echoangle]

You don’t need internet to run JS though. And the JS seems to be pretty sandboxed in normal viewers too, so a pdf file shouldn’t make network requests on its own. As long as there is no iframe-like content I don’t see how rendering a document would ever need network.