Cunningham, who is averaging 12.5 PPG and 4.5 RPG for Dayton through two games, suffered the injury on a hard dunk in the final seconds of the game. The sophomore from Chicago began to scream as he fell to the floor.
Dayton staffers then carried him off the court and took him back to the locker room.
After the game, Dayton coach Archie Miller said Cunningham, who last played for Bradley during the 2014-15 season, could miss significant time after sitting out last year due to NCAA rules for transfers.
"[The] concern is with both Josh's knee and his ankle, or lower leg area," Miller told reporters after the game. "It's uncertain what it is exactly, but we could be looking at being without him for some time."
The school had no additional comment, per Doug Hauschild, the team's spokesman.
This is just the latest challenge for a Dayton team that's dealt with its share of issues in recent months. Kendall Pollard, who averaged 10.3 PPG last season, has not played during the regular season due to a thigh bruise.
In May, center Steve McElvene collapsed and died as the result of a previously undiagnosed cardiac issue.