Upvote:1
No, there is no catholic teaching that serpents had legs.
As you say, NABRE assumes Genesis as allegorical, therefore I would take their description of the serpent as allegorical.
That is, allegorically "the serpent had legs" - as in, was in right standing with God (before Satan's fall). Then "lost the legs" / was punished meaning is no longer in the right standing with God.