Microsoft Edge Chakra Engine Type Confusion Remote Code Execution Vulnerability (CVE-2016-7201)

1. Vulnerability Overview & Root Cause

This vulnerability is a critical Type Confusion (CWE-843) flaw residing in the legacy Chakra JavaScript scripting engine (chakra.dll) used by Microsoft Edge. The root cause lies in the engine's failure to properly validate and handle object types during optimization or array manipulation processes. This allows an attacker to force the engine to treat an object of one type as if it were of a different type, leading to memory safety violations.

2. Exploitation Mechanics & Attack Scenario

An attacker exploits this vulnerability by hosting a specially crafted website containing malicious JavaScript and enticing a user to visit the site. When the Chakra engine processes the malicious script (often involving complex array operations or prototype chain modifications), it bypasses type checks. This leads to an information disclosure (leaking memory addresses) and subsequently allows the attacker to construct an arbitrary read/write primitive in memory, leading to reliable Remote Code Execution (RCE) under the context of the logged-in user.

3. Infrastructure & Business Impact

As a vulnerability listed in the CISA KEV (Known Exploited Vulnerabilities) catalog, CVE-2016-7201 has been actively exploited in the wild. Successful exploitation allows attackers to compromise endpoint systems, establish initial access within corporate networks, and potentially deploy ransomware or exfiltrate sensitive business data.