Divi <= 4.27.6 - Authenticated (Contributor+) Stored Cross-Site Scripting via Dynamic Content (Legacy JSON Format) Shortcode

The Divi theme for WordPress is vulnerable to Stored Cross-Site Scripting via the Dynamic Content feature's legacy JSON format in all versions up to, and including, 4.27.6. This is due to two compounding flaws: (1) the save-time sanitization filter `et_builder_sanitize_dynamic_content_fields()` only searches for dynamic content markers in the `@ET-DC@...@` format, but the rendering engine also supports a legacy JSON format that is silently converted at render time, completely bypassing the save-time filter, and (2) the `post_meta_key` resolver in `et_builder_filter_resolve_default_dynamic_content()` does not apply `wp_kses_post()` to the resolved meta value when `enable_html` is set to `on`, passing raw `get_post_meta()` output directly to the page. 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.