Microsoft Security Response Center

**What type of information could be disclosed by this vulnerability?** An attacker who successfully exploited this vulnerability could potentially read small portions of heap memory.

**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, privileges required is low (PR:L). Does the attacker need to be in an authenticated role on the Exchange Server?** Yes, the attacker must be authenticated.

**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, the attack complexity is high (AC:H). What does that mean for this vulnerability?** Successful exploitation of this vulnerability requires an attacker to take additional actions prior to exploitation to prepare the target environment.

**How do I get the update for a Windows App?** The Microsoft Store will automatically update affected customers. It is possible for customers to disable automatic updates for the Microsoft Store. The Microsoft Store will not automatically install this update for those customers. You can get the update through the store by following this guide: Get updates for apps and games in Microsoft Store. Note that Process Monitor is only available as part of an MSIX package called Sysinternals Suite.

A remote code execution vulnerability exists when Microsoft .NET Framework fails to properly validate input before loading libraries. An attacker who successfully exploited this vulnerability could take control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. To exploit the vulnerability, an attacker would first need to access the local system with the ability to execute a malicious application. The security update addresses the vulnerability by correcting how .NET validates input on library load.

**According to the CVSS metric, the attack vector is local (AV:L). Why does the CVE title indicate that this is a remote code execution?** The word **Remote** in the title refers to the location of the attacker. This type of exploit is sometimes referred to as Arbitrary Code Execution (ACE). The attack itself is carried out locally. For example, when the score indicates that the **Attack Vector** is **Local** and **User Interaction** is **Required**, this could describe an exploit in which an attacker, through social engineering, convinces a victim to download and open a specially crafted file from a website which leads to a local attack on their computer.

**According to the CVSS metric, privileges required is low (PR:L). What does that mean for this vulnerability?** Any authenticated attacker could trigger this vulnerability. It does not require admin or other elevated privileges.

**According to the CVSS metric, privileges required is low (PR:L). Does the attacker need to be in an authenticated role on the Exchange Server?** Yes, the attacker must be authenticated.