XSS Auditor in Google Chrome prior to 57.0.2987.98 for Mac, Windows, and Linux and 57.0.2987.108 for Android allowed detection of a blocked iframe load, which allowed a remote attacker to brute force JavaScript variables via a crafted HTML page.
https://security.gentoo.org/glsa/201704-02
https://chromereleases.googleblog.com/2017/03/stable-channel-update-for-desktop.html
http://www.securityfocus.com/bid/96767