The full-back is the second Palace player in a week to suffer a bad injury after Eberechi Eze ruptured his Achilles last week.
Eze is expected to be sidelined until 2022 and Ferguson will have surgery that will further delay his Palace debut.
Ferguson has not played for Palace since joining from West Brom last summer because of injury.
He was initially set to move to Selhurst Park in January 2020, before a routine medical by Palace picked up a knee issue and the move collapsed.
That injury was still an issue when Ferguson signed for Palace, and he uffered a setback during his rehab before then suffering a thigh strain.
Roy Hodgson did not want to rush Ferguson back this season in order to allow for a full pre-season this summer, but those plans have been scuppered after his latest injury.
There is confidence that Ferguson will make a full recovery, and that he and Eze will help one another through their respective rehabilitations.
The two injuries, however, are a blow to Palace’s plans to evolve a younger squad next season, with Eze and Ferguson now going to be absent for the start of next season.