An issue was discovered in Squiz Matrix from 5.3 through to 5.3.6.1 and 5.4.1.3. An information disclosure caused by a Path Traversal issue in the 'File Bridge' plugin allowed the existence of files outside of the bridged path to be confirmed.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2017-5706
http://devalias.net/devalias/2017/09/07/squiz-matrix-multiple-vulnerabilities/