This Vulnerability Details post about a vulnerability in the plugin SG Optimizer 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.
When it comes to blame for the poor state of web security one of the parties that should get more blame than they seem to get are web hosts. Not only do they often poorly handle security themselves, but increasingly they have been partnering with really bad security companies, allowing those security companies to cause even more problems. SiteGround is one of those web hosts, with their partnership with Sucuri (which in turns is owned by another web host, GoDaddy, with a horrible security record of their own). Sucuri is a company that among too many issues to go through, tries to scare people in to hiring them to do unneeded work, lacks a basic understanding of security, and causes their customers websites to remain insecure when they were easily fixed by people not claiming to have the level expertise that Sucuri claims to have.