The young striker is being watched by the Hammers leading up to the winter market.
Paderborn sports director Martin Przondziono told BILD: "He has huge potential, is not finished in his development.
"The rumours that he is already transferred to West Ham, I have also heard. But nobody has contacted us yet. That's why I'm not crazy."
Mamba has scored five goals in nine games for Paderborn and is tied to the club until 2022.