The Snap Creek Duplicator plugin before 1.3.28 for WordPress (and Duplicator Pro before 3.8.7.1) allows Directory Traversal via ../ in the file parameter to duplicator_download or duplicator_init.
https://snapcreek.com/duplicator/docs/changelog/?lite
https://cwe.mitre.org/data/definitions/23.html
http://packetstormsecurity.com/files/164533/WordPress-Duplicator-1.3.26-Arbitrary-File-Read.html