The company closely associated with WordPress, Automattic, has the most popular WordPress security plugin by installs, Jetpack. It has 5+ millions installs according to wordpress.org. Recently another piece of Automattic, WPScan claimed a competing plugin, All In One WP Security, which has 1+ million installs had contained a reflected cross-site scripting (XSS) vulnerability (emphasis ours):

The plugin does not validate, sanitise and escape the redirect_to parameter before using it to redirect user, either via a Location header, or meta url attribute, when the Rename Login Page is active, which could lead to an Arbitrary Redirect as well as Cross-Site Scripting issue. Exploitation of this issue requires the Login Page URL value to be known, which should be hard to guess, reducing the risk [Read more]