So, I will change the secret word for now (1-2 hours) to fix some stuff the user mention here (thanks!). And to the one who post the snake game, stop it, I need to code! ;)
Since you can insert arbitrary JS, it feels like you could write a loop that ajax posts a bunch of new webspaces when someone visits a webspace. Might look into protecting againt that.
The site doesn't seem to work, says "Wrong secret word" for hackernews.
Is there a list of pages people have made?
So with out src & href you can't have links, seem like a massive limitation. Was trying to a submit a personal site with external links, guess it's no use now.
There's srcset, and things like generating content with JS, inline css base64 images (background: url(data:...), and lots of other loopholes. The author is going to re-live a lockdown path many others have gone through ;)
After then, the word will be the same as before.