Before scrolling down in the first paragraph of the article it already says: "wanted to share with you a detailed write-up of the levels, why they're vulnerable, and how to exploit them.". I don't think it's necessary; if you don't want to read it because you're still playing you just don't continue reading the article.

Edit: And the CTF has ended, so no harm done.

The CTF has ended.

My bad, indeed, the bookmark is still viciously looking at me every day, so I was under the impression I'd still might finish it this weekend.

So spoiler alert suggestion revoked...