**tl;dr**

+ CRLF Injection in Headed Key in Werkzeug `headers.set`
+ Using CRLF Injection at `/?user=` to Get XSS at `/helloworld`
+ Make the admin visit `/?user=<PAYLOAD>` and `/helloworld` using cache poison or bug in regex(uninteded)

Original writeup (https://blog.bi0s.in/2023/08/07/Web/0_CSP-Securinets-Quals2023/).