The CSPSource::schemeMatches function in WebKit/Source/core/frame/csp/CSPSource.cpp in the Content Security Policy (CSP) implementation in Blink, as used in Google Chrome before 52.0.2743.82, does not apply http :80 policies to https :443 URLs and does not apply ws :80 policies to wss :443 URLs, which makes it easier for remote attackers to determine whether a specific HSTS web site has been visited by reading a CSP report. NOTE: this vulnerability is associated with a specification change after CVE-2016-1617 resolution.