Sometimes technology do more harm than good. If such brain technology is made, the danger of it being hacked or manipulated is real. They can steal someone's data and use it.
I read 2 years ago that a Russia billionaire has invested on cyborg which will be half human and robot in year 2030, I don't know how visible this is but an underground research might be ongoing where humans will be used as lab rat undermining the person's right.
Just yesterday, Australia parliament are debating on using a technology that will scan the faces of all citizen and they don't need a warrant to do that. The human right president in Australia and the citizens are kicking against it as their right to privacy will be denied.

All these information when gotten might hacked like you said and used to harm that person