The Flying Images: Optimize and Lazy Load Images for Faster Page Speed plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'comment' parameter in all versions up to, and including, 2.4.15 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. A first-time commenter's submission requires a single administrator approval under the default comment_previously_approved setting; however, once approved, all subsequent comments from the same name and email pair bypass moderation, and the injected script executes for every visitor — including administrators viewing the post from the front end.