The Red Devils are yet to welcome a new striker to the club in the summer transfer window amid persistent speculation surrounding the future of Cristiano Ronaldo.
With Anthony Martial currently nursing a hamstring injury, Ronaldo led the line against Brentford at the weekend but was powerless to prevent his side from slumping to a humiliating 4-0 defeat.
United are desperately in need of a revival, and with a crunching tie against Liverpool up next, Cunha's signing wouldn't have come at a better time.