The message states that a number of community's usernames and e-mail addresses have been accessed:

"We are writing to let you know that on Friday, May 24, 2019 we discovered an in-progress attack on our systems. The hackers also obtained passwords in their encrypted form (for technical people: all passwords were salted and hashed with bcrypt). This means that our user passwords remain unreadable by external parties."

According to Canva, they immediately took steps to fix the issue and reported the situation to authorities:

"As soon as we were notified we immediately took steps to identify and remedy the cause and have reported the situation to authorities (including the FBI)."

The full message can be seen here: https://www.vpntesting.com/wp-content/uploads/2019/05/data-breach-canva-1.png

We haven't got a reply from Canvas yet about the number of users affected.