The Category and Taxonomy Image plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the '_category_image' parameter in versions up to, and including, 1.0.0 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with editor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.