Home prices are booming. So far, 2018 has posted the strongest growth since 2005. “About 60% of all U.S. metros saw an acceleration in the rate of price increases through February this year,” according to Housing Wire. Since mid-2012, real home prices have increased 28%, according to data from the American Enterprise Institute. Entry-level home prices are up about double that rate. In contrast, over the same period household income has barely kept pace with inflation. The current pace of home-price inflation is increasing the risk of another housing bubble.

The root of the problem is declining underwriting standards. In April Freddie Mac announced an expansion of its 3% down-payment mortgage, the better to compete with the Federal Housing Administration and Fannie Mae . Such moves propel home prices upward. Because government agencies guarantee about 80% of all home-purchase mortgages, their underwriting standards guide the market.

Making lending even more dangerous, CNBC recently reported that “credit scores may go up” because new regulatory guidance allows delinquent taxes to be excluded when calculating credit scores. These are only some of the measures that “expand the credit box” and qualify ever-shakier borrowers for mortgages.

During the last crisis, easy credit led home prices to rise at an unsustainable pace, leading marginally qualified borrowers to stretch themselves thin. Millions of Americans’ dreams became nightmares when the housing market turned. The lax underwriting terms that helped borrowers qualify for a mortgage haunted many households for the next decade.

As many as 10 million families lost their homes to foreclosure during the recession and housing crisis, according to Pew. This happened despite federal programs that modify mortgage payment terms to prevent foreclosure. While the home-price bubble affected homes at all price levels, the largest percentage gains and subsequent declines occurred in lower-priced markets.