Apple has released a tech note regarding security enhancements included in iPhone OS 2.2. Here is a synopsis of the changes that apply to security for the iPhone and iPod Touch:
CoreGraphics Changes to CoreGraphics prevent maliciously crafted websites from causing unexpected application termination or arbitrary code execution.
ImageIO Changes to ImageIO prevent the use of maliously crafted TIFF images from causing unexpected application termination, arbitrary code execution or device reset/reboot.
Networking Changes to Networking were made to insure that the correct encryption level for PPTP VPN connections is at the right level when it was often lower … Read more