TORONTO -- The Canada Mortgage and Housing Corporation says the country's housing sector is facing a high degree of vulnerability to market instability for the eighth straight quarter.

The Crown corporation attributes the vulnerability to overvaluation and price acceleration in Toronto, Vancouver, Victoria, and Hamilton.

It rated Edmonton, Calgary, Saskatoon, Regina as having moderate levels of vulnerability and Winnipeg, Montreal and Halifax among those with low risks.

CMHC says it is seeing signs of moderate overheating in Vancouver although price growth has been slowing over the last two quarters and detached properties in some areas are seeing declining prices.

In Toronto, CMHC says sales continued to trend lower in the first quarter of 2018, well below the threshold for overheating.

CMHC's quarterly report uses overheating, acceleration of home prices, overvaluations and overbuilding to assess the country's real estate markets.