SAS/Internet 9.4 build 1520 and earlier allows local file inclusion. The samples library (included by default) in the appstart.sas file, allows end-users of the application to access the sample.webcsf1.sas program, which contains user-controlled macro variables that are passed to the DS2CSF macro.
View the template here CVE-2021-41569.yaml
References:
https://www.mindpointgroup.com/blog/high-risk-vulnerability-discovery-localfileinclusion-sas