EWWW Image Optimizer <= 8.7.7 - Reflected Cross-Site Scripting via REQUEST_URI Parameter Key

The EWWW Image Optimizer plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via REQUEST_URI Parameter Key in all versions up to, and including, 8.7.7 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. Successful exploitation requires that the enable_help option is active, as the vulnerable HelpScout Beacon script block is only emitted when that setting is enabled.