WPBakery Page Builder <= 8.7.4 - Authenticated (Subscriber+) Stored Cross-Site Scripting via 'data' Parameter

The WPBakery Page Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'data' parameter in all versions up to, and including, 8.7.4 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with subscriber-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The wp_kses_post sanitization applied during save does not neutralize the payload because the malicious script content is base64-encoded as plain alphanumeric text with no HTML tags to strip; the vc_raw_html shortcode template then decodes and echoes this content unescaped at render time.