2 threads/requests colliding at same time, resulting in unexpected behavior of application.

the time at which they collide is coined as race window

It’s a Business Logic Flaw.

Types of Race Conditions:

• Classic
• Multi Step

Limit overrun race conditions

exceed some kind of limit imposed by the business logic of the application

eg -

• Redeeming a gift card multiple times
• Rating a product multiple times
• Withdrawing or transferring cash in excess of your account balance
• Reusing a single CAPTCHA solution
• Bypassing an anti-brute-force rate limit

The whole thing is a subtype of time of check to time of use (TOCTOU) flaw.