Mapster WP Maps <= 2.0.5 - Unauthenticated Stored Cross-Site Scripting via 'config.loading.background' Parameter

The Mapster WP Maps plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 2.0.5. This is due to the /wp-json/mapster-wp-maps/save-mapmaker REST route being registered with a permission_callback that unconditionally returns true (no capability check, no nonce), together with the mapster_write_config_to_acf() helper only sanitizing string config values with sanitize_text_field() — which strips HTML tags but leaves quote characters intact — and the mapster_wp_map shortcode renderer in mapster_wordpress_maps_shortcode_display() concatenating the stored loading_background_color value into a single-quoted inline style attribute without esc_attr(). This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.