CVE-2026-56157: Microsoft SharePoint Server Spoofing Vulnerability

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-14 · updated 2026-10-28
Weakness: CWE-284

Description

Improper access control in Microsoft Office SharePoint allows an authorized attacker to perform spoofing over a network.

Affected products

Microsoft SharePoint Server: before 16.0.19725.20434; 2016, 2019 — fixed in 16.0.19725.20434
Microsoft SharePoint Server Subscription Edition: from 16.0.0 before 16.0.19725.20434 — fixed in 16.0.19725.20434
Microsoft Sharepoint Enterprise Server 2016: from 16.0.0 before 16.0.5561.1001 — fixed in 16.0.5561.1001
Microsoft SharePoint Server: from 16.0.0 before 16.0.10417.20175 — fixed in 16.0.10417.20175

How to fix

Upgrade to a fixed version: Microsoft SharePoint Server 16.0.19725.20434; Microsoft SharePoint Server Subscription Edition 16.0.19725.20434; Microsoft Sharepoint Enterprise Server 2016 16.0.5561.1001; Microsoft SharePoint Server 16.0.10417.20175. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56157

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