[londons_explore]

Both cases are the same.

Alice sends Bob an email and Bob then shares it with an evil 3rd party spell check extension... Alice's privacy has now been breached without her consent.

Alice posts her contact info to her wall, and her friend Bob (who has read access) shares it with a third party (Cambridge Analytica). Alice's privacy has now been breached without her consent.

Cambridge analytica collected the bulk of their private data with the consent of a friend of the victim.