That could come from a change in the labour market or pressure from mortgage rates which have already begun to rise.
Leung said the highly leveraged were most at risk although the Reserve Bank had tried to mitigate that to some degree with the introduction of loan-to-value ratios.
It was hard to say how much of a rise in interest rates would put pressure on people without looking more closely at the composition of mortgages, she said.
"As a sector as a whole it is vulnerable. But it is hard to quantify."
Research showed those with high loan-to-value ratios were most at risk with those types of loans more likely to be held by investors. First-home buyers were less likely to walk away from a home compared to investors, she said.
Australia's love affair with property has pushed that country's residential housing market to an eye-watering value of A$6.2 trillion.
The analysis, based on extensive surveys of 26,000 Australian households, compiled by Digital Finance Analytics, examined how much headroom households have to rising rates, taking account of their income, size of mortgage, whether they have paid ahead, and other financial commitments.
And the results were distressing.
It showed that about 20 per cent of homeowners would find themselves in mortgage difficulty if interest rates rose by 0.5 per cent or less.
An additional 4 per cent would be troubled by a rise between 0.5 per cent and 1 per cent.
Almost half of homeowners (42 per cent) would find themselves under financial pressure if home loan interest rates were to increase from their average of 4.5 per cent today to the long term average of 7 per cent.
"This is important because we now expect mortgage rates to rise over the next few months, as higher funding costs and competitive dynamics come into pay, and as regulators bear down on lending standards," Digital Finance Analytics wrote.
The major banks have already started increasing their home loan rates this year in Australia, despite the market broadly expecting the Reserve Bank of Australia to keep the cash rate steady at 1.5 per cent this year.
additional reporting news.com.au