During a security research I found an authenticated Stored XSS vulnerability.

The name of the plugin is: Scroll To Top < 1.4.1

Description

The plugin does not 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)

POC

Put the following payload in the "Text" settings of the plugin and save: 

"autofocus onfocus=alert(/XSS/)//

The XSS will be triggered when accessing the settings again   

Additional information

WPSCAN link: https://wpscan.com/vulnerability/f730f584-2370-49f9-a094-a5bc521671c1

Plugin has more than 10,000+ active installations.