The EWWW Image Optimizer WordPress plugin before 8.7.7 does not properly escape image attribute values when it rewrites page output, allowing authenticated users with author-level access and above to inject arbitrary JavaScript that is stored in published content and executes in the browser of any user who later views the affected page.
https://wpscan.com/vulnerability/334f14d5-f97b-4ec5-9b42-bb0803ae1668/