decor.io XSS vulnerability

Vulnerable URL: https://decor.io/site/fb-page-151152128416048/dsf/services/ResourceProvider?handler=paypal=eyJwYXRoIjoiL3RhYl8yNTY1Nzk1MTEwNjM3NzciLCJ2ZXJzaW9uSWQiOiJ2MTg5NTg0NDQyIn0-=l512311914=151152128416048...