I've found a stored xss in unifi.ubnt.com
Step 1: Login to unifi.ubnt.com
Step 2: Connect latest unifi controller with unifi.ubnt.com via cloud access.
Step 3: Create site with any name in that controller.
Step 4: Click on launch site in unifi.ubnt.com then you will again redirect to unifi.ubnt.com with controls.
Step 5: Create Network with xss payload "><img src=x onerror=prompt(document.cookie)>
Step 6: XSS will execute.
Note : force WebRTC should we enable.
I've attached screenshot of the same. let me know if you need more info.
Best Regard Shubham