ElementsKit Lite < 3.5.3 - Contributor+ Stored XSS via Image Comparison Widget

Description

The plugin is vulnerable to Stored Cross-Site Scripting via the plugin image comparison widget's before/after labels due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.