Buzsaky limped off at Old Trafford in midweek and a scan has confirmed an anterior cruciate ligament injury.
"It's a massive blow for us," said caretaker manager Gareth Ainsworth.
"Akos is a unique talent and was just starting to hit peak form again following a spell on the sidelines with an ankle injury.
"I'm devastated we've lost him, but all we can do is offer him support and wish him all the best with his recovery."