[misterbwong]

The difference is that the contents of this website can be crafted by the attacker directly via the URL without having to do anything to the host.

[anamexis]

How is that a meaningful attack vector, unique from webpages in general?

[ddtaylor]

In this exact context it's likely not a problem, but essentially this is a ready to go XSS attack. As far as I can tell there is no CORS or domain level protections, so an "attacker" here could easily do anything else with any client-side data being used by any other "site" on the domain.

Let's say I make a little chat app that stores some history or some other data in local browser storage or cookies. Any other site can just as easily access all of that information. An "attacker" could link you to a modified version of the chat site that relays all of your messages to their server while still making it otherwise look like it's just the normal chat. It would also retain any client side information you had previously entered like your nick name or chat history, since it's stored in local storage.

Most of the time sanitizing input, like ensuring users don't have HTML in their names or comments, combined with domain-level separation and CORS policies ensures that one site can't do things that "leak" into another. It's the reason most of the time no matter how bad people mess things up Facebook getting hacked in your browser doesn't compromise your Google account.

[Syntaf]

1. Find existing smol being shared around

2. Modify the parameters to hijack any relevant content

3. Reshare the smol site with your changes under the guise it’s the original link