The W4 Post List WordPress plugin before 2.4.6 does not validate and escape some of its block options 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/ddb10f2e-73b8-444c-90b2-5c84cdf6de5c