Simple Android PDF viewer based on pdf.js and content providers. The appdoesn't require any permissions. The PDF stream is fed into the sandboxedWebView without giving it access to the network, files, content providers orany other data.

Content-Security-Policy is used to enforce that the JavaScript and stylingproperties within the WebView are entirely static content from the APK assetsalong with blocking custom fonts since pdf.js handles rendering those itself.

It reuses the hardened Chromium rendering stack while only exposing a tinysubset of the attack surface compared to actual web content. The PDF renderingcode itself is memory safe with dynamic code evaluation disabled, and even ifan attacker did gain code execution by exploiting the underlying web renderingengine, they're within the Chromium renderer sandbox with less access than itwould have within the browser.