Newcastle's goalkeeping problems are well documented and neither Karl Darlow or Rob Elliot inspire the utmost confidence it seems.
Benitez tried and failed to bring in a new keeper during the summer but speculation has mounted that the Spanish manager is going to try again this month.
And Don Balon reports that the former Real Madrid coach has offered Casilla an escape route from the Bernabeu.
Real's imminent capture of Kepa Arrizabalaga will push Casilla even further down the pecking order in Madrid and the 31-year-old might consider a move.
Benitez previously spent £5.3 million on signing Casilla - who has one Spain cap - in 2015 and a reunion with his former boss looks on the cards.
Casilla, who has one Spain cap, has only managed 22 Primera Division appearances since joining the Spanish giants and has often played second fiddle to Keylor Navas.