From YOUCAT, fact 90:
90: Did Jesus work miracles, or are they just pious tales?
Jesus really worked miracles, and so did the APOSTLES. The New Testament authors refer to real incidents.
Even the oldest sources tell of numerous miracles, even the raising of the dead, as a confirmation of Jesus’ preaching: “But if it is by the Spirit of God that I cast out demons, then the kingdom of God has come upon you” (Mt 12:28). The miracles took place in public; some of the persons involved were known by name, for instance, blind Bartimaeus (Mk 10:46-52) or Peter’s mother-in-law (Mt 8:14-15). There were also miracles that in those Jewish circles were considered shocking and outrageous (for example, the cure of a crippled man on the SABBATH, the cure of lepers). Nevertheless they were not disputed by contemporary Judaism.