Former Yahoo CEO Marissa Mayer reportedly praised her "friend," former Uber CEO Travis Kalanick, at an event on Tuesday and suggested he might not have known about the toxic culture at Uber because the company grew so quickly.

"I just don't think he knew," Mayer said, according to the San Francisco Chronicle. "When your company scales that quickly, it's hard."

Kalanick stepped down from the CEO role earlier this month under pressure from investors, following months of news about rampant sexism and other cultural problems at Uber. An internal investigation suggested that standard human resources practices were not enforced at the company, which has more than 12,000 employees, and at least 20 employees were fired. Several executives close to Kalanick, including senior VP Emil Michael, also left in the wake of the allegations.

Kalanick remains on the board of Uber while the company searches for several new executives, including a CEO and a COO.

Read the full report at the San Francisco Chronicle.

More From CNBC

• Facebook had a plan to promote flu shots, but pulled the plug
  

• Op-ed: While my son battles leukemia, the health care system is under assault
  

• Cyberattack hits the world's biggest shipping company