In Splunk Enterprise versions below 9.2.2, 9.1.5, and 9.0.10 and Splunk Cloud Platform versions below 9.1.2312.200, a low-privileged user that does not hold the admin or power Splunk roles could create notifications in Splunk Web Bulletin Messages that all users on the instance receive.
https://securityaffairs.com/165204/security/splunk-enterprise-and-cloud-platform-flaws.html
https://research.splunk.com/application/4b7f368f-4322-47f8-8363-2c466f0b7030