Megyn Kelly got approval from higher-ups at NBC before launching her hair-raising attack on Jane Fonda, Page Six has learned — but we’re told that prominent members of the organization were then stunned by how far the broadside went.

Peacock Network insiders fear that the take-down — in which Kelly dredged up Fonda’s “Hanoi Jane” episode to argue that the actress was in no position to “say what’s offensive” — will make it even harder for Kelly to book celebrity guests on her show in case they suffer the same fate.