In Splunk versions below 9.0.8 and 9.1.3, the “mrollup” SPL command lets a low-privileged user view metrics on an index that they do not have permission to view. This vulnerability requires user interaction from a high-privileged user to exploit.
https://research.splunk.com/application/ee69374a-d27e-4136-adac-956a96ff60fd/