Every CTF has one, here's your obligatory calculator web challenge!
Some tips to guide your way:
- mathjs is part of the solution, but only a tiny part. there is no mathjs 0day, you won't get JS execution through mathjs!
- hm, why isn't DOMPurify used by default? maybe you should look into differences between DOMPurify and Sanitizer API...
- the intended solution does not require you to find any 0days.
First Solve: justCatTheFish