> The plugin seeks permission to do three things; "read and change all data on the websites you visit," "manage your downloads," and "communicate with cooperating native applications." [...]<p>> it's likely that the extension itself is harmless enough<p>That seems unlikely given Adobe's history of truly awful security flaws. It wasn't that long ago when they thought that it would be a good idea for their add-on to pre-render PDFs in RAM silently in the background, including executing any embedded code without any sandboxing. Combined with browsers' prefetching of urls in a page (so that it would load quicker in case you clicked it), this caused a number of rootkit and other malware infections - from links that people didn't even click in search results and URLs served up in advertising or in comments/forum posts.<p>The only permission needed by a PDF viewer should be 'display PDF document content'. It shouldn't need to read or change other data, manage downloads, or communicate with anything to display an e-book or document. If it does, it's probably not harmless.