Samsung is rolling out Android 4.1.2 update for the N7105, which is the LTE version of Galaxy Note 2. This is not a leak but an official release that you can download from here. This is a complete ROM, not an OTA which means it will delete all of your installed apps.
This new firmware (Android 4.1.2) will not, however, delete the data on internal SD and external micro SD card. To flash it, you will need ODIN (link). Put your phone in download mode and press the Start button to start flashing.
New Android 4.1.2 features include:
New additions to Notification Toggles
Notification Panel can now be customized
Brightness slider in Notification Panel can now be disabled
Multi-View can be disabled
Smoother and improved Web browser
Status bar’s color has been changed from grey to black
Improved Samsung keyboard
New Ink Effect on lock screen
New Group Cast application