Apple iPhone users warned of JailbreakMe security risks – Telegraph: “”

Although the jailbreakMe operation is completely benign it does make use of a serious loophole in mobile Safari.
The exploit requires the user to click on a PDF link in a website which can then take advantage of the way the PDF viewer loads and displays fonts.

Jailbroken iPhones curiously enough, have access to an app via Cydia that prompts for authorisation every time a program or service tries to open a PDF.