CVE-2026-3604: Kcseopro Wp Seo Structured Data Schema

Medium severity, CVSS 4.9. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Kcseopro Wp Seo Structured Data Schema: up to and including 2.8.1

Published 2026-05-12. Last modified 2026-06-17.