One of the ways we help to improve the security of WordPress plugins, not just for our customers, but for everyone using them, is the proactive monitoring of changes made to plugins in the Plugin Directory to try to catch serious vulnerabilities. Through that we caught an authenticated arbitrary file upload vulnerability in the plugin Child Themes Helper, which is also exploitable through cross-site request forgery (CSRF). That occurs in an AJAX accessible function and it looks like a number of other ones are also insecure and contain vulnerabilities, one of the more serious we will detail in a follow up post.

The possibility of this vulnerability is also flagged by our Plugin Security Checker, so you can check plugins you use to see if they might have similar issues with that tool. [Read more]