On Tuesday, Apple released a minor bug fix version for iPhone OS pushing the version number from 3.1.2 to 3.1.3. The new update is mainly for bug fixes including:
  • Improves accuracy of reported battery level on iPhone 3GS
  • Resolves issue where third-party apps would not launch in some instances
  • Fixes bug that may cause an app to crash when using the Japanese Kana keyboard

According the release note, this release also offers a number of security fixes for various known issues:

  • CoreAudio: A buffer overflow exists in the handling of mp4 audio files. Playing a maliciously crafted mp4 audio file may lead to an unexpected application termination or arbitrary code execution. This issue is addressed through improved bounds checking.
  • ImageIO: A buffer underflow exists in ImageIO’s handling of TIFF images. Viewing a maliciously crafted TIFF image may lead to an unexpected application termination or arbitrary code execution.
  • Recovery Mode: A memory corruption issue exists in the handling of a certain USB control message. A person with physical access to the device could use this to bypass the passcode and access the user’s data.
  • WebKit: Multiple input validation issues exist in WebKit’s handling of FTP directory listings. Also, Mail may load remote audio and video content when remote image loading is disabled
Despite with all the bug fixes and minor improvements, please hold off the OS upgrade if you are using a jailbroken iPhone. Most of the jailbreak tools (e.g. blackra1n) are not yet compatible with iPhone OS 3.1.3. As of now, only redsn0w offers jailbreaking support for OS 3.1.3 on certain devices (only iPhone 2G & 3G). So, what you have to do is stay away from the upgrade.