A remote code execution vulnerability exists when Microsoft Windows PDF Library improperly handles objects in memory. The vulnerability could corrupt memory in 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 on Windows 10 systems with Microsoft Edge set as the default browser, an attacker could host a specially crafted website that contains malicious PDF content and then convince users to view the website. The attacker could also take advantage of compromised websites, or websites that accept or host user-provided content or advertisements, by adding specially crafted PDF content to such sites. Only Windows 10 systems with Microsoft Edge set as the default browser can be compromised simply by viewing a website. The browsers for all other affected operating systems do not automatically render PDF content, so an attacker would have no way to force users to view attacker-controlled content. Instead, an attacker would have to convince users to open a specially crafted PDF document, typically by way of an enticement in an email or instant message or by way of an email attachment.
The update addresses the vulnerability by modifying how affected systems handle objects in memory.