In Splunk Enterprise Security (ES) versions below 7.1.2, an attacker can use investigation attachments to perform a denial of service (DoS) to the Investigation. The attachment endpoint does not properly limit the size of the request which lets an attacker cause the Investigation to become inaccessible.
https://research.splunk.com/application/bb85b25e-2d6b-4e39-bd27-50db42edcb8f/