Only ten days passed since Apple released iOS 4.3.4/4.2.9 for iPhone, iPad, iPod touch / Verizon CDMA iPhone 4. Now what literally is out of the blue, Apple has released 4.2.10 for the CDMA Verizon iPhone 4 and iOS 4.3.5 for iPhone, iPad and iPod touch. Direct download link to official iOS 4.2.10 ipsw can be found at the end of this post.
The reason why Apple released iOS 4.3.4 in the first place was to patch that vulnerability in mobile Safari that was used by JailbreakMe 3.0 to jailbreak iPad 2 on iOS 4.3.3 and iPhone, iPad 1, iPod touch on iOS 4.3 - 4.3.3. Comex released PDF Patcher 2 in Cydia alongside JailbreakMe 3.0 in order to patch that very exploit but allowing you to keep the jailbreak. Naturally, Apple had to release an official software update so as to patch that vulnerability. So that became the reason behind iOS 4.3.4 / 4.2.9 release merely ten days ago.
The iOS 4.2.10 changelog isn't that extensive. Apple only provides fixing a security issue with certificate validation as the reason behind iOS 4.2.10 release for Verizon iPhone 4.
It should be kept in mind that the Verizon iPhone 4 is susceptible to the Limera1n bootrom exploit and can be jailbroken on iOS 4.2.9 and iOS 4.2.10, regardless of the fact that for now it is going to be a tethered jailbreak. No iOS 4.2.10 untethered jailbreak is coming. So if you would like to keep your untethered Verizon iPhone 4 jailbreak, please do not upgrade from iOS 4.2.8.
Restoring your Verizon iPhone 4 to iOS 4.2.10 is a piece of cake. Either download iOS 4.2.10 ipsw from the link provided at the bottom on your computer, connect your device to iTunes and if you are on a Mac, press and hold the alt key while you click on Restore. Windows users have to press and hold the Shift key while clicking on Restore. Then select your iOS 4.2.10 ipsw and you're good to go. If you don't want to put yourself in such a hassle, simply connect your CDMA Verizon iPhone 4 to the computer, launch iTunes and wait for it to prompt you that a new firmware update, iOS 4.2.10 is available for your iPhone 4. Click on Download and Install when prompted and iTunes will automatically take care of the rest for you.
Download iOS 4.2.10 for Verizon CDMA iPhone 4. [Official Apple Link]