Apple will no longer allow users to update or restore an iOS device to iOS 4.3.3 and the signing window for 4.3.3 has been closed, meaning that you can no longer restore a device to 4.3.3 in iTunes without previously saved SHSH blobs from that firmware. Apple released its promised iOS 4.3.4 software towards the end of last week to fix a security vulnerability in mobile Safari that made the latest JailbreakMe exploit possible, but it will also kill all other untethered jailbreaks too…………..
Apple is no longer signing the iOS 4.3.3 firmware, meaning if you did not save your iOS 4.3.3 SHSH blobs you will no longer be able to downgrade your iDevice to the iOS 4.3.3 firmware. Additionally if you have a Wifi + 3G iPad 2 you will be no longer able to downgrade to the iOS 4.3.3 firmware even if you have saved SHSH blobs. The iOS 4.3.4 firmware was released to combat Comex’s new PDF vulnerability and if you are looking to downgrade to the iOS 4.3.3 firmware you can download it or any other firmware version. Additionally if you are stuck on the iOS 4.3.4 firmware you can still Jailbreak it tethered using RedSn0w 0.9.8b3 (except the iPad 2 unfortunately).