Inappropriate use of www mismatch redirects in browser navigation in Google Chrome prior to 61.0.3163.79 for Mac, Windows, and Linux, and 61.0.3163.81 for Android, allowed a remote attacker to potentially downgrade HTTPS requests to HTTP via a crafted HTML page. In other words, Chrome could transmit cleartext even though the user had entered an https URL, because of a misdesigned workaround for cases where the domain name in a URL almost matches the domain name in an X.509 server certificate (but differs in the initial "www." substring).