Apple has released today iOS 4.3.4 software update.
Affected products: iPad, iPod touch (3rd generation), iPhone 4, iPod touch (4th generation), iPhone 3GS, Product Security
iOS 4.3.4 Software Update resolves issues related to:
Viewing a maliciously crafted PDF file may lead to an unexpected application termination or arbitrary code execution
Malicious code running as the user may gain system privileges
View full article on http://support.apple.com/kb/HT4802