The Jetpack WordPress plugin before 13.8, Jetpack Boost WordPress plugin before 3.4.8 use regexes in the Site Accelerator features when switching image URLs to their CDN counterpart. Unfortunately, some of them may match patterns it shouldn’t, ultimately making it possible for contributor and above users to perform Stored XSS attacks
https://wpscan.com/vulnerability/15f278f6-0418-4c83-b925-b1a2d8c53e2f/