Samsung is already rolling out the May security patch to the Galaxy Note 4 in India. The update comes in at 378.38MB, and there isn't much in the way of what's new according to the changelog, which only mentions the usual stability and bug fixes. What is interesting though is the Android security patch level, which is listed as May 1 2016.
The phone picked up the Android 6.0.1 Marshmallow update earlier this month, and has received an update with the April security patch just four days ago. If you're on the Galaxy Note 4 in India, be sure to head into your device's settings to download the latest update. As for what's fixed in the May security update, we'll have to wait for Google to formally announce it next week.