Microsoft SharePoint Server Security Feature Bypass Vulnerability

What is CVE-2026-55040?

CVE-2026-55040 is a vulnerability classified as Weak Authentication, affecting Microsoft SharePoint Enterprise Server 2016 (affected versions: 16.0.0 – < 16.0.5561.1001), Microsoft SharePoint Server 2019 (affected versions: 16.0.0 – < 16.0.10417.20175), and Microsoft SharePoint Server Subscription Edition (affected versions: 16.0.0 – < 16.0.19725.20434). This vulnerability is rated Critical, with a CVSS score of 9.1. This vulnerability has been observed being exploited in the wild.

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Overview

Original source data

Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.

Affected products and scope

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Technical details

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Exploitability

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Technical impact

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Business impact

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Remediation

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Detection

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Sources (6)

GCVE / Vulnerability-Lookup

microsoft (CNA)

National Vulnerability Database (NVD)

CISA Known Exploited Vulnerabilities

Other references

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Microsoft SharePoint Enterprise Server 2016

Microsoft

Microsoft SharePoint Server 2019

Microsoft

Microsoft SharePoint Server Subscription Edition

Microsoft

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