Unfortunately, this issue lowers the bar for exploiting a months-old vulnerability.

The older ongoing problem is that any person can create a new Experian account with a new email address, and answer a few credit-related quiz to take over somebody's credit file. When doing this Experian will helpfully even offer to unlock the credit file and you can reset security questions etc. All without the consent of the victim. All the "security" systems are bypassed.

This new vulnerability means you need even less information to take over somebody's credit/identity. You can get the answers to their quiz directly from Experian's own systems. That makes it a bigger deal.