RSS Aggregator by Feedzy < 4.1.1 - Contributor+ Stored XSS

The RSS Aggregator by Feedzy WordPress plugin before 4.1.1 does not validate and escape some of its block options before outputting them back in the page, which could allow users with a role as low as contributor to perform Stored Cross-Site Scripting attacks which could be used against high privilege users such as admins.