see #6 of the T & C's for full details
https://www.msccruisesusa.com/-/media/us/documents/Booking-Terms-and-Conditions-221115-FINAL.pdf
6. PASSPORT, VISAS AND MINORS Passengers must hold fully valid passports for the whole duration of the Cruise Package with a passport expiration date at least 6 months after the return date. Certain countries, including the USA and Russia, require machine-readable and digital photo passports.