[rvnx]

Why would that be the maximum damage ? This XSS is particularly dangerous because you are running your script on the same domain where the user is logged-in so you can pretty much do anything you want under his session.

In addition this is widespread. It's golden for any attacker.

[0x3f]

Because modern cookie directives and browser configs neuter a lot of the worst XSS outcomes/easiest exploit paths. I would expect all the big sites to be setting them, though I guess you never know.

[rvnx]

I would not be that confident as you can see: on their first example, they show Discord and the XSS code is directly executed on Discord.com under the logged-in account (some people actually use web version of Discord to chat, or sign-in on the website for whatever reason).

If you have a high-value target, it is a great opportunity to use such exploits, even for single shots (it would likely not be detected anyway since it's a drop in the ocean of requests).

Spreading it on the whole internet is not a good strategy, but for 4000 USD, being able to target few users is a great value.

Besides XSS, phishing has its own opportunity.

Example: Coinbase is affected too though on the docs subdomain and there are 2-step, so you cannot do transactions directly but if you just replace the content with a "Sign-in to Coinbase / Follow this documentation procedure / Download update", this can get very very profitable.

Someone would pay 4000 USD to receive 500'000 USD back in stolen bitcoins).

Still, purely with executing things under the user sessions there are interesting things to do.

[promiseofbeans]

> some people actually use web version of Discord to chat, or sign-in on the website for whatever reason

Beside this security blunder on Discord’s part, I can see only upsides to using a browser version rather than an Electron desktop app. Especially given how prone Discord are to data mining their users, it seems foolish to let them out of the web sandbox and into your system

[tptacek]

Again, here you have not so much sold a vulnerability as you have planned a heist. I agree, preemptively: you can get a lot of money from a well-executed heist!

[rvnx]

Do you want to execute actions as logged-in user on high-value website XXX ?

If yes -> very useful

[tptacek]

Nobody is disputing that a wide variety of vulnerabilities are "useful", only that there's no market for most of them. I'd still urgently fix an XSS.

[rvnx]

There is a market outside Zerodium, it's Telegram. Finding a buyer takes time and trust, but it has definitively higher value than 4k USD because of its real-world impact, no matter if it is technically lower on the CVSS scores.

[GoblinSlayer]

AIU this feature is SSS, not XSS, so XSS protections don't apply.