Summary
Impact: Remote Code Execution. Microsoft rating: Critical. Not known to be exploited — Exploitation Less Likely. Customer action: Required.
Details
According to the CVSS metric, privileges required is low (PR:L). What does that mean for this vulnerability?
Any authenticated attacker could trigger this vulnerability. It does not require admin or other elevated privileges.
How could an attacker exploit the vulnerability?
In a network-based attack, an authenticated attacker, as at least a Site Owner, could write arbitrary code to inject and execute code remotely on the SharePoint Server.
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.
Security updates
16.0.5552.1002 — https://support.microsoft.com/help/5002868
16.0.10417.20128 — https://support.microsoft.com/help/5002870
16.0.19725.20280 — https://support.microsoft.com/help/5002863
Vulnerabilities 1
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High 8.8
Microsoft SharePoint Server Remote Code Execution Vulnerability
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
Revision history
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#1
Information published.
References
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CVE-2026-40365 Microsoft SharePoint Server Remote Code Execution Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40365
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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