In “OpenCMS”, versions 10.5.0 to 11.0.2 are affected by a stored XSS vulnerability that allows low privileged application users to store malicious scripts in the Sitemap functionality. These scripts are executed in a victim’s browser when they open the page containing the vulnerable field.
https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25968
https://github.com/alkacon/mercury-template/commit/800945f5d02346c633c7aef9f5d596d7dedc8fb5