Windows HTML Platforms Security Feature Bypass Vulnerability

What kind of security feature could be bypassed by successfully exploiting this vulnerability? A security feature bypass vulnerability exists when the MSHTML platform fails to validate the correct Security Zone of requests for specific URLs. This could allow an attacker to cause a user to access a URL in a less restricted Internet Security Zone than intended. To exploit this vulnerability, an attacker could email or otherwise provide a specially crafted URL to a victim and convince them to click on it. The security update addresses the vulnerability by correcting security feature behavior to properly map affected URLs to the correct Security Zone.

According to the CVSS metric, user interaction is required (UI:R). What interaction would the user have to do? An attacker must send the user a malicious file and convince them to open it.

According to the CVSS metric, successful exploitation of this vulnerability could lead to some loss of integrity (I:L) and some loss of availability (A:L). What does that mean for this vulnerability? An attacker can craft a malicious file or send a malicious URL that would evade Security Zone tagging, resulting in a limited loss of integrity and availability of security features utilized by browsers and some custom applications.

The Security Updates table indicates that this vulnerability affects all supported versions of Microsoft Windows except Windows Server 2008, Windows Server 2008 R2, and Windows Server 2012. Why are IE Cumulative updates listed for Windows Server 2012 R2? While Microsoft has announced retirement of the Internet Explorer 11 application on certain platforms and the Microsoft Edge Legacy application is deprecated, the underlying MSHTML, EdgeHTML, and scripting platforms are still supported. The MSHTML platform is used by Internet Explorer mode in Microsoft Edge as well as other applications through WebBrowser control. The EdgeHTML platform is used by WebView and some UWP applications. The scripting platforms are used by MSHTML and EdgeHTML but can also be used by other legacy applications. Updates to address vulnerabilities in the MSHTML platform and scripting engine are included in the IE Cumulative Updates; EdgeHTML and Chakra changes are not applicable to those platforms. To stay fully protected, we recommend that customers who install Security Only updates install the IE Cumulative updates for this vulnerability.