The Brizy Page Builder plugin <= 2.3.11 for WordPress was vulnerable to stored XSS by lower-privileged users such as a subscribers. It was possible to add malicious JavaScript to a page by modifying the request sent to update the page via the brizy_update_item AJAX action and adding JavaScript to the data parameter, which would be executed in the session of any visitor viewing or previewing the post or page.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-38344
• https://www.wordfence.com/blog/2021/10/multiple-vulnerabilities-in-brizy-page-builder-plugin-allow-site-takeover/