The scary thing about CNN is they believe they are unbiased.
Gwen Ifill asked Gloria Borger (who works for CNN now) on PBS's Washington Week in Review about the planted question(er), and Borger replied that CNN did vet the general but didn't discover the link to Hillary! -- although she didn't address whether CNN can't have known what the plant intended to ask the GOP candidates.
She said instead that it was a fair and good question to ask.
I conclude from the Ifill-Borger exchange that even liberals concede that it was a below-the-belt stunt that CNN is responsible for having failed to filter.