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Privacy Statement Third-Party Cookies AcceptRejectManage cookies MSRC  Customer Guidance  Security Update Guide  Vulnerabilities  CVE-2026-64921 Microsoft SharePoint Server Elevation of Privilege Vulnerability New On this page  CVE-2026-64921  Subscribe RSS PowerShell  API  CSAF Security Vulnerability Released: Aug 11, 2026 Assigning CNA Microsoft CVE.org link CVE-2026-64921  Impact Elevation of Privilege Max Severity Critical Weakness CWE-306: Missing Authentication for Critical Function CVSS Source Microsoft Vector String CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C Metrics CVSS:3.1 8.8 / 7.7  Base score metrics: 8.8 / Temporal score metrics: 7.7  Expand all  Collapse all Metric Value   Base score metrics(8) Attack Vector Network Attack Complexity Low Privileges Required Low User Interaction None Scope Unchanged Confidentiality High Integrity High Availability High   Temporal score metrics(3) Exploit Code Maturity Unproven Remediation Level Official Fix Report Confidence Confirmed Please see Common Vulnerability Scoring System for more information on the definition of these metrics. Executive Summary Missing authentication for critical function in Microsoft Office SharePoint allows an authorized attacker to elevate privileges over a network. Exploitability The following table provides an exploitability assessment for this vulnerability at the time of original publication. Publicly disclosed No Exploited No Exploitability assessment Exploitation Less Likely FAQ How could an attacker exploit the vulnerability? An authenticated attacker with access to the domain could perform remote code execution on the SharePoint server to elevate themselves to SharePoint admin. 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. Acknowledgements Michael Maturi with Google/Mandiant https://google.com/ Kn1ght Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure. See Acknowledgements for more information. Security Updates To determine the support lifecycle for your software, see the Microsoft Support Lifecycle. Release date Descending  Edit columns  Download  Filters  Product Family  Max Severity  Impact  Platform   Clear Release date  Product Platform Impact Max Severity Article Download Build Number Assigning CNA Title: Release date, Content: Aug 11, 2026 Microsoft SharePoint Server Subscription Edition - Elevation of Privilege Critical Title: Knowledge Base Articles for Microsoft SharePoint Server Subscription Edition, Content:, 1 link 5002893  Title: Download Security Update for Microsoft SharePoint Server Subscription Edition, Content:, 1 link Security Update  Title: Build numbers, Content: 16.0.19725.20522 Title: Assigning CNA, Content: Microsoft Title: Release date, Content: Aug 11, 2026 Microsoft SharePoint Server 2019 - Elevation of Privilege Critical Title: Knowledge Base Articles for Microsoft SharePoint Server 2019, Content:, 2 links 5002894  5002896  Title: Download Security Update for Microsoft SharePoint Server 2019, Content:, 2 links Security Update  Security Update  Title: Build numbers, Content: 16.0.10417.20198 16.0.10417.20198 Title: Assigning CNA, Content: Microsoft Title: Release date, Content: Aug 11, 2026 Microsoft SharePoint Enterprise Server 2016 - Elevation of Privilege Critical Title: Knowledge Base Articles for Microsoft SharePoint Enterprise Server 2016, Content:, 2 links 5002905  5002906  Title: Download Security Update for Microsoft SharePoint Enterprise Server 2016, Content:, 2 links Security Update  Security Update  Title: Build numbers, Content: 16.0.5565.1001 16.0.5565.1001 Title: Assigning CNA, Content: Microsoft All results loaded Loaded all 3 rows Disclaimer The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply. Revisions version revisionDate description 1.0 Aug 11, 2026 Information published.  How satisfied are you with the MSRC Security Update Guide? Rating  Broken  Bad  Below average  Average  Great!  Your Privacy Choices Consumer Health Privacy Privacy & Cookies