Google Chrome before 4.0.249.89 attempts to make direct connections to web sites when all configured proxy servers are unavailable, which allows remote HTTP servers to obtain potentially sensitive information about the identity of a client user via standard HTTP logging, as demonstrated by a proxy server that was configured for the purpose of anonymity.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A14500
https://exchange.xforce.ibmcloud.com/vulnerabilities/56212
http://www.vupen.com/english/advisories/2010/0361
http://www.securityfocus.com/bid/38177
http://sites.google.com/a/chromium.org/dev/Home/chromium-security/chromium-security-bugs
http://securitytracker.com/id?1023583
http://secunia.com/advisories/38545
http://googlechromereleases.blogspot.com/2010/02/stable-channel-update.html