W3 Total Cache < 2.10.6 - Unauthenticated Stored XSS via LazyLoad Background Mutator

Description

The plugin is vulnerable to Stored Cross-Site Scripting via Comment Content via LazyLoad Background Mutator due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This requires the "Lazy Load Images" feature with "Process background images" to be enabled, and the malicious comment to be approved by a moderator before execution is triggered.