Microsoft Security Update Guide · SharePoint
Microsoft SharePoint Server 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 Enterprise Server 2016: KB5002891
16.0.5561.1001 - Microsoft SharePoint Server Subscription Edition: KB5002882
16.0.19725.20434 - Microsoft SharePoint Server 2019: KB5002883
16.0.10417.20175
- Microsoft SharePoint Enterprise Server 2016: KB5002891
- 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
14 jul 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 Enterprise Server 2016 | KB5002891 · Security Update | 16.0.5561.1001 |
| Microsoft SharePoint Server Subscription Edition | KB5002882 · Security Update | 16.0.19725.20434 |
| Microsoft SharePoint Server 2019 | KB5002883 · Security Update | 16.0.10417.20175 |
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?
- An authorized attacker must send the user a malicious link and convince the user to open it.
- 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 | 14 jul 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.
