Speed Optimizer < 7.8.1 - Contributor+ Stored XSS via Image Tag Attributes

Description

The plugin is vulnerable to Stored Cross-Site Scripting via Image Tag Attributes, 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. This is only exploitable when the site administrator has enabled the Lazy Load Media option in the plugin settings.