Stored XSS on app.crowdsignal.com + your-subdomain.survey.fm via Embed Media

Hello there, I found a stored xss vulnerability. Steps: 1. Go to `https://app.crowdsignal.com/dashboard` 2. Create a quiz. 3. Go to `https://app.crowdsignal.com/quizzes/{your-quiz-id}/question` 4. Add `Multiple Choice` 5. Put a name to answer 1. 6. Click Add media button. {F901543} 7. Select Embed Media 8. Paste this: `[wpvideo w0MiG12E]` 9. Insert it. 10. Open `Burp Suite` and click `Save` button. 11. Return to burp suite and paste this payload to `media[23168664]` parameter: `[wpvideo%20w0MiG12Exx1\"><svg/onload=prompt(document.domain)>]` 12. Forward the request and refresh the page. You will see xss alert. Also go to `https://app.crowdsignal.com/sharing/quiz/{your-quiz-id}/` and copy survey.fm link. Go to it and you will see xss alert. ## Impact Stealing cookies Regards, @mygf