The OTP Login & Register Woocommerce plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'fb-config' Setting in all versions up to, and including, 2.7.3 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. On multisite installations where administrators do not hold the unfiltered_html capability, this vulnerability can be leveraged to target the network super administrator.