Course

The Code Review Snippet challenges provide brief pieces of code that contain vulnerabilities, encouraging you to spot the issues without assistance initially. Once you have tried to find the flaws, you can watch the accompanying video to either confirm your findings or gain a deeper understanding of the problem.

In the TypeScript 02 challenge, we examine a piece of code that implements a CORS middleware for an Express application. The video explains the structure and function of the code, highlighting a critical vulnerability where the origin header from the client request is echoed back, allowing any origin to send CORS requests to the application. This can lead to security issues, such as leaking sensitive information through cross-origin requests.