The CSPSource::hostMatches function in WebKit/Source/core/frame/csp/CSPSource.cpp in the Content Security Policy (CSP) implementation in Google Chrome before 47.0.2526.73 accepts an x.y hostname as a match for a *.x.y pattern, which might allow remote attackers to bypass intended access restrictions in opportunistic circumstances by leveraging a policy that was intended to be specific to subdomains.
https://security.gentoo.org/glsa/201603-09
https://codereview.chromium.org/1367933003
https://code.google.com/p/chromium/issues/detail?id=534542
http://www.ubuntu.com/usn/USN-2825-1
http://www.securitytracker.com/id/1034298
http://www.securityfocus.com/bid/78416
http://www.debian.org/security/2015/dsa-3415
http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00017.html
http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00016.html
http://googlechromereleases.blogspot.com/2015/12/stable-channel-update.html