CVE-2026-64900: Microsoft SharePoint Server Spoofing Vulnerability
CVE-2026-64900 is a spoofing vulnerability in Microsoft SharePoint Server, rated Important by Microsoft, with a CVSS 3.1 base score of 7.3 (High). An attacker can exploit it remotely over the network, with low privileges and only if a user takes an action. Microsoft has not reported exploitation in the wild. The EPSS model estimates a 0.65% probability of exploitation activity in the next 30 days, higher than 51% of all scored vulnerabilities. Microsoft released the fix on 11 August 2026 in the August 2026 Patch Tuesday, delivered through 5 security updates (KB5002905, KB5002906, KB5002894, KB5002896 and more). It affects 3 products in 1 product family (Microsoft Office).
Key facts
- CVE ID
- CVE-2026-64900
- Severity
- High CVSS 7.3
- Microsoft severity
- Important
- Impact
- Spoofing
- Exploited in the wild
- No
- Publicly disclosed
- No
- Weakness
- CWE-79
- EPSS
- 0.65% (percentile 51%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- August 2026 Patch Tuesday
- Product families
- Microsoft Office
CVSS score and vector
Microsoft scores CVE-2026-64900 at 7.3 (temporal 6.4) using CVSS 3.1. Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C
| Metric | Value |
|---|---|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | Required |
| Scope | Unchanged |
| Confidentiality impact | High |
| Integrity impact | High |
| Availability impact | None |
| Exploit code maturity | Unproven |
| Remediation level | Official fix |
| Report confidence | Confirmed |
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.
Frequently asked questions (Microsoft)
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.
How could an attacker exploit this vulnerability?
An authenticated attacker with permissions to add or modify content on an affected SharePoint page could store malicious script content in the page. The script could run in the security context of another user when that user views and interacts with the affected content, potentially allowing the attacker to access or modify SharePoint data available to that user.
Affected products (3)
Microsoft Office
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Microsoft SharePoint Enterprise Server 2016 | KB5002905 KB5002906 | Security Update Security Update | 16.0.5565.1001 16.0.5565.1001 | Maybe Maybe |
| Microsoft SharePoint Server 2019 | KB5002894 KB5002896 | Security Update Security Update | 16.0.10417.20198 16.0.10417.20198 | Maybe Maybe |
| Microsoft SharePoint Server Subscription Edition | KB5002893 | Security Update | 16.0.19725.20522 | Maybe |
Security updates (5)
NIST NVD data
- NVD status
- Analyzed
- NVD CVSS
- 7.3 (HIGH)
- NVD weakness
- CWE-79
- Published to NVD
- NVD last modified
Affected configurations (CPE)
| Product | Vulnerable versions |
|---|---|
| sharepoint server | before 16.0.19725.20522 |
| sharepoint server 2016 | all listed versions |
| sharepoint server 2019 | all listed versions |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64900 (Vendor Advisory, Patch)
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |