365Fanatic / M365 Status / Security advisories / CVE-2026-64921

Microsoft Security Update Guide · SharePoint

Microsoft SharePoint Server Elevation of Privilege Vulnerability

Microsoft · EN CVE-2026-64921 Critical Action required CVSS 8.8

Published 11 aug 2026

What does this mean?

Elevation of Privilege. An attacker can gain more rights than they should have, for example admin rights.
It can be exploited over the network (including from the internet if the service is reachable there), with an ordinary user account and without any user action.
CVSS 8.8 out of 10: high. Microsoft rates it Critical.
No attacks reported; Microsoft expects exploitation to be less likely.
What should you do? Install the security update for the version you run (or a later cumulative update):
- Microsoft SharePoint Server Subscription Edition: KB5002893 16.0.19725.20522
- Microsoft SharePoint Server 2019: KB5002894 16.0.10417.20198
- Microsoft SharePoint Server 2019: KB5002896 16.0.10417.20198
- Microsoft SharePoint Enterprise Server 2016: KB5002905 16.0.5565.1001
- Microsoft SharePoint Enterprise Server 2016: KB5002906 16.0.5565.1001
This applies to SharePoint Server you run yourself. Microsoft updates SharePoint Online in Microsoft 365.

Microsoft Office SharePoint · Elevation of Privilege

Missing authentication for critical function in Microsoft Office SharePoint allows an authorized attacker to elevate privileges over a network.

SharePoint Office / Microsoft 365 Apps

How do I check if I am affected?

SharePoint Server: check and update

Check your farm build in the SharePoint Management Shell:
```
(Get-SPFarm).BuildVersion
```
Or in Central Administration → Upgrade and Migration → Check product and patch installation status.
If the build is equal to or higher than the build under "Affected products and updates" below, this vulnerability is fixed. A later cumulative update includes the fix too.

Otherwise install the update on every server in the farm, then run the SharePoint Products Configuration Wizard, or:

PSConfig.exe -cmd upgrade -inplace b2b -wait -cmd applicationcontent -install -cmd installfeatures -cmd secureresources -cmd services -install

You do not need to update SharePoint Online in Microsoft 365; Microsoft does that.

Key facts

Released

11 aug 2026

Impact

Elevation of Privilege

Max severity

Critical

Weakness

CWE-306: Missing Authentication for Critical Function

CVSS 3.1

8.8 / 7.7 (base / temporal)

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

Publicly disclosed

Exploited

Exploitability assessment

Exploitation Less Likely

Customer action required

Yes

Links

Microsoft Security Update Guide · CVE.org

CVSS metrics

Base score metrics
Attack Vector	Network
Attack Complexity	Low
Privileges Required	Low
User Interaction	None
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High
Temporal score metrics
Exploit Code Maturity	Unproven
Remediation Level	Official Fix
Report Confidence	Confirmed

Affected products and updates

Product	Update	Build
Microsoft SharePoint Server Subscription Edition	KB5002893 · Security Update	`16.0.19725.20522`
Microsoft SharePoint Server 2019	KB5002894 · Security Update	`16.0.10417.20198`
Microsoft SharePoint Server 2019	KB5002896 · Security Update	`16.0.10417.20198`
Microsoft SharePoint Enterprise Server 2016	KB5002905 · Security Update	`16.0.5565.1001`
Microsoft SharePoint Enterprise Server 2016	KB5002906 · Security Update	`16.0.5565.1001`

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.

Revisions

Version	Date	Note
1	11 aug 2026	Information published.

What changed in Microsoft 365 this week? →

View at Microsoft → ← All security advisories

Source: Microsoft Security Update Guide. 365Fanatic is not affiliated with Microsoft.