Apple released iOS 4.3.3 and iOS 4.2.8 firmware for iPhone,iPad and iPod touch.First you need to Downgrade iOS 4.3.3 to old Firmware,After that you can jailbreak your Device running iOS 4.2.8 and iOS 4.3.3.iPhone Dev Team has released Untethered jailbreak tool RedsnOw 0.9.6rc16 and iH8snOw has released SnOwbreeze 2.7.1 for Untethered  jailbreak iOS 4.2.8 on CDMA Verizon iPhone 4.So just follow our instruction to untethered jailbreak CDMA Verizon iPhone 4 using SnOwbreeze 2.7.1.

Follow the step to Untethered jailbreak iOS 4.2.8 using SnOwbreeze 2.7.1 :

• Step 1 : Download iTunes 10.2.2
• Step 2 : Download iOS 4.2.8 Firmware
• Step 3 : Download SnOwbreeze 2.7.1
• Step 4 : Now Run SnOwbreeze 2.7.1 on your system and click to next button.
• Step 5 : Than select Required Firmware iOS 4.2.8 IPSW & click on Browse Button.
• Step 6 : Now snOwbreeze identifying selected iPSW File than click next for process.
• Step 7 : Than Select Expert Mode and Follow Built IPSW option for creating custom firmware.
• Step 8 : Now snOwbreeze processing finishing after than message will comes Done.
• Step 9 : Than you have to enter on DFU Mode
• Step 10 : Now start iTunes 10.2.2 click there iOS icon.
• Step 11 : Now press and hold Left “Shift” button on the keyboard and then click on “Restore”
• Step 12 : Now wait for movement till iTunes Processing,dont make any silly mistakes while iTunes progressing.It Take few minutes to install iOS 4.2.8 Firmware on your Devices.
• Step 13 : Now enjoy Untethred jailbreak iOS 4.2.8 using SnOwbreeze 2.7.1

So now you done and enjoy Untethered jailbreak iOS 4.2.8 on Verizon iPhone 4 using SnOwbreeze 2.7.1.So keep updates with us for more details on jailbreak iOS 4.3.3 and iOS 4.2.8 firmware.