Corporate debt is projected to swell over the next several years, thanks to cheap money from global central banks, according to a report Wednesday that warns of a potential crisis from all that new, borrowed cash floating around.

By 2020, business debt likely will climb to $75 trillion from its current $51 trillion level, according to S&P Global Ratings. Under normal conditions, that wouldn't be a major problem so long as credit quality stays high, interest rates and inflation remain low, and there are economic growth persists.

However, the alternative is less pleasant should those conditions not persist. Should interest rates rise and economic conditions worsen, corporate America could be facing a major problem as it seeks to manage that debt. Rolling over bonds would become more difficult should inflation gain and rates raise, while a slowing economy would worsen business conditions and make paying off the debt more difficult.

In that case, a "Crexit," or withdrawal by lenders from the credit markets, could occur and lead to a sudden tightening of conditions that could trigger another financial scare.

"A worst-case scenario would be a series of major negative surprises sparking a crisis of confidence around the globe," S&P said in the report. "These unforeseen events could quickly destabilize the market, pushing investors and lenders to exit riskier positions ('Crexit' scenario). If mishandled, this could result in credit growth collapsing as it did during the global financial crisis."

In fact, S&P considers a correction in the credit markets to be "inevitable." The only question is degree.

The firm worries that investors have been overly willing in their hunt for yield to buy speculative-grade corporate debt. This has been true not only in the United States but also China, which has used borrowing to spur growth but now finds itself at an economic crossroads.