Unfortunately, there's always one time a ship is almost completely vulnerable...in port.
See also, USS COLE, Pearl Harbor 12/7/41, etc.
Out at sea, no, no one's getting close, especially since a warning has (undoubtedly) been transmitted to the ship (and all other carriers) and they are now on alert, but a pierside attack is something else again.
I do think it's extremely unlikely, and I suspect the navy has a variety of plans in place that work to prevent any such attack. It's not impossible, but I'd be surprised if anything of note happened.