A remote code execution vulnerability exists due to the way Windows Uniscribe handles objects in memory. An attacker who successfully exploited this vulnerability could take control of the 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.
There are multiple ways an attacker could exploit this vulnerability:
In a web-based attack scenario, an attacker could host a specially crafted website designed to exploit this vulnerability and then convince a user to view the website. An attacker would have no way to force users to view the attacker-controlled content. Instead, an attacker would have to convince users to take action, typically by getting them to click a link in an email or instant message that takes users to the attacker's website, or by opening an attachment sent through email.
In a file-sharing attack scenario, an attacker could provide a specially crafted document file designed to exploit this vulnerability and then convince a user to open the document file.
The security update addresses the vulnerability by correcting how Windows Uniscribe handles objects in memory.
Note that for the Office products listed in the Affected Products table, where the severity is indicated as Critical, the Preview Pane is an attack vector for this vulnerability.