Blazes still shoot fireballs when a passive mob is riding them

The top mob has the control since the Passengers update. The second issue is probably either works as intended or won't fix.

correction, both mobs controll movement, they still have their ai, so yes the blaze attacking is intended

Can some mod resolve this?

Resolve to/for what?

@[redstonehelper] As Works as Intended

If my memory doesn't fail me, if mobs ride other mobs, they have their separate AI, but the bottom mob will do the moving.
Take the Spider Jockey for example. It is a skeleton riding a spider. The spider will move the unit as one and, because its AI is programmed to do so, will attack the player like any other spider; the skeleton doesn't have a say in the matter.
The skeleton itself will act according to its AI; it will fire arrows at the player if the player comes within range. It does not take heed to the spider at all.
Therefore, if a Blaze rode a pig, the pig would do the moving (which includes going crazy if hit) and the Blaze would still fire fireballs at you.
The blaze hitting the pig would depend on the hitbox of the pig and where the fireball spawns. I did not develop Minecraft and I'm pretty sure it wasn't developed in Processing JS so I can't delve into that.
Oh, and all this was taken from before 1.9, so it might not be 100% correct, but I hope it helps.

1.9 changed this, passengers can now control movement/AI.

Is this still an issue in the most recent versions (currently that is 1.10.2, or 16w42a) of Minecraft? If so, please update the affected versions and help us keeping this ticket updated from time to time. If you are the owner/reporter of this ticket, you can modify the affected version(s) yourself.

This doesn't happen anymore in 20w29a. The blaze won't shoot fireballs at you, instead it deals collision damage.

For me, the blaze does still shoot fireballs, however they don't damage the pig.