Simple School Staff Directory <= 1.1 - Admin+ Arbitrary File Upload

Description

The plugin does not validate uploaded logo pictures to ensure that are indeed images, allowing high privilege users such as admin to upload arbitrary file like PHP, leading to RCE

Proof of Concept

As admin, upload a PHP file via the Add Logo page of the plugin (https://example.com/wp-admin/options-general.php?page=simple-schools-staff-directory%2Fsi_main.php)

The file will be located at  https://example.com/wp-content/uploads/logos/<filename.php>