"Authorize Coinbase" login prompt at secondary source -- vulnerable?

[paramind22]

I just mentioned this in another thread but I don't think many people will see it so I'm posting it here.

I just saw an "authorize Coinbase" login prompt like the way you authorize FB or Google to log you in other sites.  That's kind of scary giving another site access to your Coinbase account.  Does that mean that this gives one step towards a vulnerability if they get hacked?