Simple SEO Slideshow <= 1.2.8 - Authenticated (Contributor+) Stored Cross-Site Scripting via Shortcode Attributes

CVE-2026-8900

What is CVE-2026-8900?

The Simple SEO Slideshow plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Shortcode Attributes in all versions up to, and including, 1.2.8 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. WordPress KSES does not strip malicious shortcode attribute values on post save, allowing contributor-level users to persist payloads that execute for any visitor, including administrators reviewing the post.

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