Canada Mortgage and Housing Corporation says Toronto, Ottawa and Montreal most at risk.
The country's housing market went from a moderate to a high degree of vulnerability in the second quarter of the year.
Canada Mortgage and Housing Corporation (CMHC) says the change is due to factors such as price acceleration and overvaluation throughout the country.
The rating is also based on overheating and excess inventories.
Cities with the highest risk include Toronto, Ottawa, Hamilton and Montreal.
While Niagara doesn't get a vulnerability rating, the CMHC says the area is experiencing strong price growth.
Woman`s Body Found in Niagara Falls
Habitat for Humanity Building in Thorold
Police Target Trucks By-Passing Inspection
Bob Cole Dies at the Age of 90
Suspect Sought After Cannabis Store Robbery
Niagara Transit to Receive Gas Tax Money
Local Power Company Upgrading Technology
Police Called Concerning Armed Individual