The WPBakery Page Builder Addons by Livemesh plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `[lvca_carousel]` and `[lvca_posts_carousel]` shortcode attributes in all versions up to, and including, 3.9.4 due to insufficient input sanitization and output escaping. Specifically, shortcode attributes are encoded with `wp_json_encode()` and output into single-quoted `data-settings` HTML attributes without using `esc_attr()`, allowing attackers to break out of the attribute by injecting single quotes. 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.