Microsoft Security Update Guide · SharePoint
Microsoft Office SharePoint Spoofing Vulnerability
Published
What does this mean?
- Spoofing. An attacker can pretend to be another user or source, for example through a misleading link or page.
- It can be exploited over the network (including from the internet if the service is reachable there), with an ordinary user account and if a user takes part, for example by opening a link or file.
- CVSS 7.3 out of 10: high. Microsoft rates it Important.
- 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: KB5002908
16.0.20326.20090
- Microsoft SharePoint Server Subscription Edition: KB5002908
- This applies to SharePoint Server you run yourself. Microsoft updates SharePoint Online in Microsoft 365.
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.
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:
Or in Central Administration → Upgrade and Migration → Check product and patch installation status.(Get-SPFarm).BuildVersion - 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.
What kind of flaw is this?
- CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Input is not cleaned before it appears in a web page (cross-site scripting). An attacker can run script in another user's browser.
Key facts
Released
8 sep 2026
Impact
Spoofing
Max severity
Important
Weakness
CVSS 3.1
7.3 / 6.4 (base / temporal)
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N/E:U/RL:O/RC:CPublicly disclosed
No
Exploited
No
Exploitability assessment
Exploitation Less Likely
Customer action required
Yes
Links
CVSS metrics
| Base score metrics | |
|---|---|
| Attack Vector | Network |
| Attack Complexity | Low |
| Privileges Required | Low |
| User Interaction | Required |
| Scope | Unchanged |
| Confidentiality | High |
| Integrity | High |
| Availability | None |
| 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 | KB5002908 · Security Update | 16.0.20326.20090 |
FAQ
- 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?
- This means an authenticated user can upload malicious content, but exploitation only occurs if they convince another user to visit or interact with that content.
- 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.
- 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.
Revisions
| Version | Date | Note |
|---|---|---|
| 1 | 8 sep 2026 | Information published. |
This is in the weekly digest for week 37 · What changed this week? →
View at Microsoft → ← All security advisories
Source: Microsoft Security Update Guide. 365Fanatic is not affiliated with Microsoft.
