core/html/parser/XSSAuditor.cpp in the XSS auditor in Blink, as used in Google Chrome before 33.0.1750.117, inserts the about:blank URL during certain blocking of FORM elements within HTTP requests, which allows remote attackers to bypass the Same Origin Policy and obtain sensitive information via unspecified vectors.
Exploitability
AV:NAC:LAu:NImpact
C:PI:PA:N6.4/AV:N/AC:L/Au:N/C:P/I:P/A:N