The Ultimate Blocks WordPress plugin before 3.2.0 does not validate and escape some of its post-grid block attributes before outputting them back in a page/post where the block is embed, which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks
https://wpscan.com/vulnerability/d2e2d06b-0f07-40b9-9b87-3373f62ae1a9/