The Flash plug-in in Google Chrome before 27.0.1453.116, as used on Google Chrome OS before 27.0.1453.116 and separately, does not properly determine whether a user wishes to permit camera or microphone access by a Flash application, which allows remote attackers to obtain sensitive information from a machine's physical environment via a clickjacking attack, as demonstrated by an attack using a crafted Cascading Style Sheets (CSS) opacity property.
https://src.chromium.org/viewvc/chrome?revision=206188&view=revision
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16693
https://code.google.com/p/chromium/issues/detail?id=249335
http://habrahabr.ru/post/182706/
http://googlechromereleases.blogspot.com/2013/06/stable-channel-update_18.html
http://googlechromereleases.blogspot.com/2013/06/stable-channel-update-for-chrome-os.html