The Revslider plugin for WordPress is vulnerable to Stored Cross-Site Scripting via svg upload in all versions up to, and including, 6.6.20 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. By default, this can only be exploited by administrators, but the ability to use and configure revslider can be extended to authors.