The MStore API – Create Native Android & iOS Apps On The Cloud plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the update_user_profile() function in all versions up to, and including, 4.15.3. This makes it possible for authenticated attackers, with subscriber-level access and above, to upload arbitrary files (not including PHP files) on the affected site's server which may make remote code execution possible. This can be paired with a registration endpoint for unauthenticated users to exploit the issue.
https://plugins.trac.wordpress.org/changeset/3147900/mstore-api/trunk/functions/index.php
https://plugins.trac.wordpress.org/changeset/3147900/mstore-api/trunk/controllers/flutter-user.php
https://plugins.trac.wordpress.org/browser/mstore-api/trunk/controllers/flutter-user.php#L1053