I found a XSS  in the chat window of meet.jit.si.
Injection can be achieved by simply escaping the double-quote:
[Copy n paste the following into the chat window]
*"<script>alert("Eto ti biskvitka:\n\n"+document.cookie);</script>*
To solve this meta-character problem, all dangerous meta characters
should be escaped into their equivalent HTML-entities .
I hope this helps?
P.S. Pozdravi na vsicki Bulgari v otbora