A remote code execution vulnerability exists in Microsoft SharePoint when the software fails to check the source markup of an application package. An attacker who successfully exploited the vulnerability could run arbitrary code in the context of the SharePoint application pool and the SharePoint server farm account. Exploitation of this vulnerability requires that a user uploads a specially crafted SharePoint application package to an affected version of SharePoint. The security update addresses the vulnerability by correcting how SharePoint checks the source markup of application packages.
Is the Preview Pane an attack vector for this vulnerability? No, the Preview Pane is not an attack vector.
<a href="https://www.linkedin.com/in/jonathan-birch-ab27681/">Jonathan Birch</a> of Microsoft Office Security Team