Describe CVE-2021-24826.
What is CVE-2021-24826?
The Custom Content Shortcode WordPress plugin before 4.0.2 does not escape custom fields before outputting them, which could allow Contributor+ (v < 4.0.1) or Admin+ (v < 4.0.2) users to perform Cross-Site Scripting attacks even when the unfiltered_html is disallowed. Please note that such attack is still possible by admin+ in single site blogs by default (but won't be when the unfiltered_html is disallowed).