Extensions for Leaflet Map <= 4.7 - Authenticated (Contributor+) Stored Cross-Site Scripting

The Extensions for Leaflet Map plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `geojsonmarker` shortcode in all versions up to, and including, 4.7. This is 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.