Screaming Penguin - Source Does Matter

This is of course pretty darn low on the security list but be advised that your PDF file reader could allow malicious code to run on your system. That is if you open a maliciously designed PDF that can take advantage of external code the readers readily spawn for certain tasks. This affects all kinds of PDF readers including the Adobe products.

For more see the linked eweek article.   CERT, Adobe Warn of Flaw in PDF File Readers: eWeek