Ghast blow up netherrack with mobGriefing = false

For quite some time I've been hosting multiple servers for my friends, and in the latest few versions Ghasts blow up netherrack even though mobGriefing = false.

I did not test it with other blocks.

I'm unsure which version this started, but the problem still persists in the newest version of the game.

 

EDIT: I have set "mobGriefing = False" in the nether itself, and that fixed the problem. I assume the command is tied to dimension, or doesn't affect Nether for some reason.