Custom Content Shortcode < 4.0.2 - Authenticated Arbitrary File Access / LFI

The plugin does not validate the data passed to its load shortcode, which could allow Contributor+ (v < 4.0.1) or Admin+ (v < 4.0.2) users to display arbitrary files from the filesystem (such as logs, .htaccess etc), as well as perform Local File Inclusion attacks as PHP files will be executed. Please note that such attack is still possible by admin+ in single site blogs by default (but won’t be when either the unfiltered_html or file_edit is disallowed)

PoC

If the file is a PHP one, its content will be executed, leading to a LFI [load dir=site file=a.php] Otherwise, if can be used to access sensitive data by displaying them (such as via log files for example) [load dir=site file=.htaccess]