The 19-year-old featured in the Under-21s' 1-1 draw with Stoke City on Monday at right-back and will provide options in defence for the Cumbrians.
"Manchester United know all about us and they know we look after their players when they come up here," manager Greg Abbott told Carlisle's official website. "I've been able to have Sean watched and he has a great physical presence with his size and with the way he plays the game.
"He is very highly thought of down there and, hopefully, he will join us and fit into the squad at a time when we have picked up a few injuries."
McGinty will wear the No23 shirt at his new club and is scheduled to stay with Carlisle until Tuesday 4 December. The teenager was with Oxford at the start of the campaign and played for Morecambe on loan last season.
Corry Evans, Oliver Norwood and James Chester have all previously been loaned from United to the Brunton Park outfit.