CVE-2026-63520: Microsoft SharePoint Server Remote Code Execution Vulnerability

Overview

Severity
High (CVSS 8.1)
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Category
Remote Code Execution
Exploit Status
Not Exploited
Exploitation Likelihood
More Likely
Patch Tuesday
2026-Aug
Released
2026-08-11

Description

Improper input validation in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.

FAQ

How could an attacker exploit this vulnerability? In a network-based attack, an unauthenticated attacker could write arbitrary code to inject and execute code remotely on the SharePoint Server. According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability? A high attack complexity means that successful exploitation is complex and time‑consuming, requiring significant effort and precise conditions for an attacker to reliably exploit the vulnerability. There are multiple update packages available for some of the affected software. Do I need to install all the updates listed in the Security Updates table for the software? Yes. Customers should apply all updates offered for the software installed on their systems. If multiple updates apply, they can be installed in any order. I am running SharePoint Server 2016. Do the updates for SharePoint Enterprise Server 2016 also apply to the version I am running? Yes. The same KB number applies to both SharePoint Server 2016 and SharePoint Enterprise Server 2016. Customers running either version should install the security update to be protected from this vulnerability.

Affected Products (3)

Microsoft Office

  • Microsoft SharePoint Enterprise Server 2016
  • Microsoft SharePoint Server 2019
  • Microsoft SharePoint Server Subscription Edition

Security Updates (5)

Acknowledgments

<a href="https://x.com/stephenfewer">Stephen Fewer</a> with <a href="https://www.rapid7.com/">Rapid7</a>

Revision History

  • 2026-08-11: Information published.