CVE-2026-123391: Microsoft Office SharePoint Elevation of Privilege Vulnerability
CVE-2026-123391 is an elevation of privilege vulnerability in Microsoft Office SharePoint, rated Important by Microsoft, with a CVSS 3.1 base score of 8.8 (High). An attacker can exploit it remotely over the network, with low privileges and without user interaction. Microsoft has not reported exploitation in the wild and rates exploitation as unlikely. Microsoft released the fix on 10 November 2026 in the November 2026 Patch Tuesday, delivered through 1 security update (KB5002908). It affects 1 product in 1 product family (Microsoft Office).
Key facts
- CVE ID
- CVE-2026-123391
- Severity
- High CVSS 8.8
- Microsoft severity
- Important
- Impact
- Elevation of Privilege
- Exploited in the wild
- No
- Publicly disclosed
- No
- Exploitation likelihood
- Unlikely
- Weakness
- CWE-863
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- November 2026 Patch Tuesday
- Product families
- Microsoft Office
CVSS score and vector
Microsoft scores CVE-2026-123391 at 8.8 (temporal 7.7) using CVSS 3.1. Vector: 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
| Metric | Value |
|---|---|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality impact | High |
| Integrity impact | High |
| Availability impact | High |
| Exploit code maturity | Unproven |
| Remediation level | Official fix |
| Report confidence | Confirmed |
Description
Incorrect authorization in Microsoft Office SharePoint allows an authorized attacker to elevate privileges over a network.
Frequently asked questions (Microsoft)
How could an attacker exploit this vulnerability?
An authenticated attacker could send a specially crafted request to an affected SharePoint server to perform an operation beyond the permissions granted to their account. Successful exploitation could allow the attacker to modify protected content or administrative configuration. No additional user interaction is required.
Is the Preview Pane an attack vector for this vulnerability?
No, the Preview Pane is not an attack vector.
Affected products (1)
Microsoft Office
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| Microsoft SharePoint Server Subscription Edition | KB5002908 | Security Update | 16.0.20326.20136 |
Security updates (1)
- KB5002908 (Security Update)
NIST NVD data
- NVD status
- Awaiting Analysis
- NVD CVSS
- 8.8 (HIGH)
- NVD weakness
- CWE-863
- Published to NVD
- NVD last modified
References
Acknowledgments
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |