An attacker authenticated as an administrator can use an exposed webservice to create a PDF with an embedded attachment. By specifying the file to be an internal server file and subsequently downloading the generated PDF, the attacker can read any file on the server with no effect on integrity or availability.
https://www.securityweek.com/sap-patches-critical-vulnerability-in-netweaver/
https://securityaffairs.com/171839/security/sap-fixed-critical-ssrf-flaw-netweaver.html