Summary
Impact: Spoofing. Microsoft rating: Important. Not known to be exploited — Exploitation Less Likely. Customer action: Required.
Details
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.
Is the Preview Pane an attack vector for this vulnerability?
No, the Preview Pane is not an attack vector.
Security updates
16.0.20326.20278 — https://support.microsoft.com/help/5002945
Vulnerabilities 1
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Critical 9.0
Microsoft Office SharePoint Spoofing Vulnerability
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.
Revision history
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#1
Information published.
References
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CVE-2026-109454 Microsoft Office SharePoint Spoofing Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-109454
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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