Mashable reports today that Security Exploit Can Give Hackers Control of Your iPhone or iPad [WARNING]. You will want to be careful not to load any PDFs that you don't know for sure are safe. This is a buffer overflow bug in the PDF rendering engine having to do with font management. While obscure, it's actually the bug that was used to provide a web-based jailbreak of the iPhone running iOS 3.1.2 or higher.