WP SEO Structured Data Schema <= 2.8.1 - Authenticated (Contributor+) Stored Cross-Site Scripting via '_kcseo_ative_tab' Parameter

Description

The WP SEO Structured Data Schema plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `_kcseo_ative_tab` parameter in all versions up to, and including, 2.8.1 due to insufficient input sanitization and output 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.