CVE-2026-64897: Microsoft SharePoint Server Spoofing Vulnerability

Overview

Severity
Medium (CVSS 4.6)
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C
Category
Spoofing
Exploit Status
Not Exploited
Exploitation Likelihood
Less Likely
Patch Tuesday
2026-Aug
Released
2026-08-11

Description

Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an authorized attacker to perform spoofing over a network.

FAQ

How could an attacker exploit the vulnerability? An attacker who successfully exploited this vulnerability might be able to run their scripts in the security context of the current user by enticing the user to click on a link resulting in a cross-site scripting attack on the SharePoint Server. 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. According to the CVSS metric, user interaction is required (UI:R) and privileges required is low (PR:L). What does that mean for this vulnerability? An authorized attacker must send the user a malicious link and convince the user to open it. According to the CVSS metrics, successful exploitation of this vulnerability could lead to some loss of confidentiality (C:L), and integrity (I:L) but lead to no loss of availability (A:N). What is the impact of this vulnerability? An attacker who successfully exploited the vulnerability could view some sensitive information (Confidentiality), make changes to disclosed information (Integrity), but cannot limit access to the resource (Availability). 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.

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://th.linkedin.com/in/navaponpremkasem">Navapon Premkasem</a>, <a href="https://www.linkedin.com/in/songsit-srisura/">Songsit Srisura</a>, P1hcn

Revision History

  • 2026-08-11: Information published.