In OpenNMS Horizon, versions opennms-1-0-stable through opennms-27.1.0-1; OpenNMS Meridian, versions meridian-foundation-2015.1.0-1 through meridian-foundation-2019.1.18-1; meridian-foundation-2020.1.0-1 through meridian-foundation-2020.1.6-1 are vulnerable to CSRF, due to no CSRF protection, and since there is no validation of an existing user name while renaming a user. As a result, privileges of the renamed user are being overwritten by the old user and the old user is being deleted from the user list.
https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25930
https://github.com/OpenNMS/opennms/commit/eb08b5ed4c5548f3e941a1f0d0363ae4439fa98c
https://github.com/OpenNMS/opennms/commit/607151ea8f90212a3fb37c977fa57c7d58d26a84