A simple mu-plugin to log in as any WordPress user without a known password

If you have FTP access to a customer’s site (or if they haven’t secured their WordPress file editor), you can add this code to their site and be able to log in as any WordPress user. I developed this to help with issue that afflict only certain users. If you’ve ever done any type of technical support, you know that it’s often very important to “see what they’re seeing”. And even though this plugin would cause a huge security risk if left on their site, it is also an extremely useful way to help customers.

Before using it, I recommend changing the $_GET key to something only you’d know… just in case you forget to delete it when you’re done! (I definitely don’t use “user_id” as the key when I use this code)