This Vulnerability Details post about a vulnerability in the plugin WP Support Plus Responsive Ticket System provides the details of a vulnerability we ran across while collecting data on vulnerabliities discovered by others for our data set on vulnerabilities in WordPress plugins, so its contents are limited to customers of our service. If you are not currently a customer, you can sign up for free here. There are a lot of other reason that you will want to sign up beyond access to posts like this one, including that you would have already been warned about this vulnerability if your website was vulnerable due to it.
If you want the best information and therefore best protection against vulnerabilities in WordPress plugins we provide you that through our service.
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. That again has lead to us catching a vulnerability in a fairly popular plugin, of a type that hackers are likely to exploit if they know about it. Since the check used to spot this is also included in our Plugin Security Checker (which is now accessible through a WordPress plugin of its own), it is another of reminder of how that can help to indicate which plugins are in greater need of security review (for which we do as part of our service as well as separately).