Sony’s waterproof 6.4” Full HD Display phablet the Xperia Z Ultra just got CyanogenMod support with the first CyanogenMod 10.2 rom. CyanogenMod 10.2 is based of Android 4.3 so your effectively running Android 4.3 on your Sony Xperia Z Ultra.
An unlocked bootloader is needed with a custom recovery, click here to download the rom. The only issue with the current build is the notification leds.
* Extract boot.img from rom file, also place zip file in root of internal memory
* With phone powered off, presse and hold VOL+ and plug usb cable, this should put you into fastboot mode.
* From fastboot mode push boot.img (extracted above) by using fastboot flash boot boot.img
* Issue fastboot reboot
* when the led goes purple, press volume + or –
* from cwm install the zip