Bill Toulas reports: British classifieds site Gumtree.com suffered a data leak after a security researcher revealed that he could access sensitive personally identifiable data of advertisers simply by pressing F12 on the keyboard. When pressing the F12 key in a web browser, the application will open the developer tools console, which allows you to view a website’s source code, monitor network requests, and view error messages produced by the website. Read more at BleepingComputer.