The Image Sizes on Demand plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via PHP_SELF Server Variable in all versions up to, and including, 1.3 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. The injected payload only executes in the context of an administrator, as the settings page requires the manage_options capability to render.