Code Embed < 2.5.2 - Authenticated (Contributor+) Stored Cross-Site Scripting via Custom Fields

Description

The Code Embed plugin for WordPress is vulnerable to Stored Cross-Site Scripting via custom field meta values in all versions up to, and including, 2.5.1. This is due to the plugin's sanitization function `sec_check_post_fields()` only running on the `save_post` hook, while WordPress allows custom fields to be added via the `wp_ajax_add_meta` AJAX endpoint without triggering `save_post`. The `ce_filter()` function then outputs these unsanitized meta values directly into page content without escaping. 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.