McAfee said it has found a vulnerability in Adobe Systems’ Reader program that reveals when and where a PDF document is opened. The issue emerges when some users launch a link to another file path, which calls on a JavaScript API, while Reader alerts a user when they are going to call on a resource from another place. McAfee declined to reveal the details of the vulnerability as Adobe is yet to release a patch for it. The vendor said that it has already detected a number of groups and people exploiting it, potentially for malicious purposes.
Source: https://thehackernews.com/2013/04/adobe-reader-pdf-tracking-vulnerability.html