The plugin does not implement any sanitisation on the color setting of the background of a calculator, which could allow high privilege users to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed.
Proof of Concept
1. Go to settings page available under the "Calculator" menu item.
2. Click the "Select Color" button and type the following payload the input space: </style></head><script>alert(/XSS/)</script>
3. Click the "Save Changes" button to save settings.
4. Create a new page and add the shortcode ([mcwp type="cv"]) of the calculator, for testing.
5. Visit the page to trigger XSS.