A remote code execution vulnerability exists when Microsoft Edge PDF Reader improperly handles objects in memory. The vulnerability could corrupt memory in such a way that enables an attacker to execute arbitrary code in the context of the current user. An attacker who successfully exploited the vulnerability could gain the same user rights as the current user. If the current user is logged on with administrative user rights, an attacker 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. To exploit the vulnerability, in a web-based attack scenario, an attacker could host a website that contains malicious PDF content. In addition, compromised websites and websites that accept or host user-provided content could contain specially crafted PDF content that could exploit the vulnerability. However, in all cases an attacker would have no way to force a user to view the attacker-controlled content. Instead, an attacker would have to convince a user to take action. For example, an attacker could trick a user into clicking a link that takes the user to the attacker's site. The security update addresses the vulnerability by modifying how Microsoft Edge PDF Reader handles objects in memory.