CVE-2026-123390: Microsoft Office SharePoint Remote Code Execution Vulnerability
CVE-2026-123390 is a remote code execution 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. 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-2026-123390
- Severity
- High CVSS 8.8
- Microsoft severity
- Important
- Impact
- Remote Code Execution
- Exploited in the wild
- No
- Publicly disclosed
- No
- Weakness
- CWE-502
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- November 2026 Patch Tuesday
- Product families
- Microsoft Office
CVSS score and vector
Microsoft scores CVE-2026-123390 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
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
Frequently asked questions (Microsoft)
How could an attacker exploit the vulnerability?
An authenticated attacker with Site Owner permissions or higher could upload a specially crafted file to the targeted SharePoint Server and craft specialized API requests to trigger deserialization of file's parameters. This would enable the attacker to perform remote code execution in the context of the SharePoint Server.
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-502
- Published to NVD
- NVD last modified
References
Acknowledgments
- 41ae55e9310ff27fa6f26af4727e5590
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |