In Splunk Enterprise versions below 9.0.5, 8.2.11, and 8.1.14, and Splunk Cloud Platform versions below 9.0.2303.100, a low-privileged user can trigger an HTTP response splitting vulnerability with the ‘rest’ SPL command that lets them potentially access other REST endpoints in the system arbitrarily.
https://research.splunk.com/application/e615a0e1-a1b2-4196-9865-8aa646e1708c/