Update the WordPress AdSanity premium plugin to the latest available version (at least 1.8.2). Vulnerability author note: new version doesn’t allow Contributor users to upload files but still allows Author+ users to do so, therefore if you have Author users registered on your blog, you may exercise extreme caution.
Jerome Bruandet (NinTechNet) discovered and reported this Broken Access Control vulnerability in WordPress AdSanity Plugin. This vulnerability has been fixed in version 1.8.2.