The Print, PDF, Email by PrintFriendly plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'content_position_css' parameter in all versions up to, and including, 5.5.10 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.