Summary
Impact: Elevation of Privilege. Microsoft rating: Important. Not known to be exploited — Exploitation Unlikely. Customer action: Required.
Details
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.
Security updates
16.0.20326.20136 — https://support.microsoft.com/help/5002908
Vulnerabilities 1
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High 8.8
Microsoft Office SharePoint Elevation of Privilege Vulnerability
Incorrect authorization in Microsoft Office SharePoint allows an authorized attacker to elevate privileges over a network.
Revision history
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#1
Information published.
References
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CVE-2026-123391 Microsoft Office SharePoint Elevation of Privilege Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-123391
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Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
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Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
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Common Vulnerability Scoring System
https://www.first.org/cvss