File upload logic in Apache Struts is flawed. An attacker can manipulate file upload params to enable paths traversal and under some circumstances this can lead to uploading a malicious file which can be used to perform Remote Code Execution.

This issue affects Apache Struts: from 2.0.0 before 6.4.0.

Users are recommended to upgrade to version 6.4.0 at least and migrate to the new file upload mechanism https://struts.apache.org/core-developers/file-upload . If you are not using an old file upload logic based on FileuploadInterceptor your application is safe.

You can find more details in  https://cwiki.apache.org/confluence/display/WW/S2-067