The plugin does not sanitise and escape some of its settings, which could allow 
high privilege users such as admin to perform Stored Cross-Site Scripting 
attacks even when the unfiltered_html capability is disallowed 
(for example in multisite setup)

Put the following payload in the Settings > Thermometer > Currency settings: 

" style=animation-name:rotation onanimationstart=alert(/XSS/)//

Save the changes, the XSS will be triggered when accessing the 
settings again, as well as in the frontend in pages 
where the [thermometer] is embed.