WebKit, as used in Google Chrome before 15.0.874.102 and Android before 4.4, allows remote attackers to bypass the Same Origin Policy and conduct Universal XSS (UXSS) attacks via vectors related to (1) the DOMWindow::clear function and use of a selection object, (2) the Object::GetRealNamedPropertyInPrototypeChain function and use of an __proto__ property, (3) the HTMLPlugInImageElement::allowedToLoadFrameURL function and use of a javascript: URL, (4) incorrect origins for XSLT-generated documents in the XSLTProcessor::createDocumentFromSource function, and (5) improper handling of synchronous frame loads in the ScriptController::executeIfJavaScriptURL function.