A cross-site scripting (XSS) vulnerability in the forms component of Mautic before 3.2.4 allows remote attackers to inject executable JavaScript via mautic[return] (a different attack method than CVE-2020-35124, but also related to the Referer concept).
https://www.mautic.org/blog/community/security-release-all-versions-mautic-prior-2-16-5-and-3-2-4
https://www.horizon3.ai/disclosures/mautic-unauth-xss-to-rce
https://github.com/mautic/mautic/security/advisories/GHSA-42q7-95j7-w62m