bindings/scripts/v8_types.py in Blink, as used in Google Chrome before 43.0.2357.130, does not properly select a creation context for a return value's DOM wrapper, which allows remote attackers to bypass the Same Origin Policy via crafted JavaScript code, as demonstrated by use of a data: URL.
Software security is not security software. Here we're concerned with topics like authentication, access control, confidentiality, cryptography, and privilege management.