- Annoying “Open PDF in Edge” Default Option Puts Windows 10 Users at Risk. From Softpedia. Microsoft has released today its monthly security patch, and one of the five security bulletins labeled as critical concerns a remote code execution (RCE) flaw in its standard PDF rendering library that could be exploited when opening PDF files. The issue, tracked as CVE-2016-3319, is found in the Microsoft Windows PDF Library, the default Windows utility used to open, read, and render PDF files, embedded by default in a couple of apps such as Edge. An attacker could craft malicious code, add it to the header of a PDF file, and host the file on a Web server.