My Email Shortcode <= 0.91 - [Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')]

The My Email Shortcode plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'subject' shortcode attribute in the 'my-email' shortcode in all versions up to, and including, 0.91 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.