The JCH Optimize WordPress plugin before 5.0.1 does not properly restrict a directory path provided to one of its administrative image-browsing features to within the site, allowing high-privilege users, administrators on single-site and sub-site administrators on multisite, to enumerate directories and file names outside the web root.
https://wpscan.com/vulnerability/73e664a8-9075-4fe6-9af4-b6f5d2ccfe3c/