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Microsoft Security Response CenterCVE-2026-55040

Microsoft SharePoint Server Security Feature Bypass Vulnerability

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

Read the vendor bulletin Get alerts for Microsoft SharePoint Enterprise Server
9.1CVSS out of 10Critical severity
Scope

What the vendor says is affected

  • Microsoft SharePoint Enterprise Server 2016
  • Microsoft SharePoint Server 2019
  • Microsoft SharePoint Server Subscription Edition

Versions the vendor lists as fixed

  • 16.0.5561.1001
  • 16.0.10417.20175
  • 16.0.19725.20434
Next step

What the vendor recommends

Install KB5002891. Install KB5002883. Install KB5002882.

Review the complete instructions on the vendor's site
Timeline

When this advisory changed

  1. Published by Microsoft Security Response Center

    The publication date reported by the vendor.

  2. Added to SecurityAlert

    We collected the advisory from the official source.

Vulnerabilities

CVEs named in this advisory

CVE-2026-55040View CVSS, KEV, EPSS, and threat context
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