You can hurt (kill) passive mobs (might be the case with hostile mobs too) in protected areas.

This issue affects

Passive mobs. (Might be able with hostile mobs too.)

How this differs from the expected behaviour

You normally shouldn't be able to hurt mobs in protected areas.

How the issue manifests itself

1. Get an mob in protected area, in this example an cat.
2. Critical (Jump) hit the cat with Fire Aspect Sword.
3. It takes fire damage.
4. It dies.

-Filip0706