The risky mortgage is making a comeback. More than a decade after home loans triggered the worst financial crisis in a generation, the strict lending requirements put in place during its aftermath are starting to erode. Home buyers with low credit scores or high debt levels as well as those lacking traditional employment are finding it easier to get credit. The loans have been rebranded. Largely gone are the monikers subprime and Alt-A, a type of mortgage that earned the nickname “liar loan” because so many borrowers faked their income and assets. Now they are called non-qualified, or non-QM, because...