CVE-2026-56157 Microsoft CVE debrief

Who should care

SharePoint Server administrators, security teams, and IT personnel responsible for vulnerability management and patching should assess exposure and apply patches for affected versions. This includes teams managing Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019, and Microsoft SharePoint Server Subscription Edition.

Why it matters

A spoofing vulnerability in Microsoft SharePoint Server could allow an authorized attacker to perform spoofing over a network. SharePoint Server administrators and security teams should assess exposure and apply patches for affected versions.

• Spoofing could lead to phishing or other malicious activities
• Verify patches have been applied to affected SharePoint Server versions
• Monitor SharePoint Server for suspicious activity

Technical summary

The vulnerability exists due to improper access control in Microsoft Office SharePoint, allowing an authorized attacker to perform spoofing over a network. Affected versions include Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019, and Microsoft SharePoint Server Subscription Edition.

Defensive priority

Apply patches for affected SharePoint Server versions

Recommended defensive actions

• Apply patches for affected SharePoint Server versions
• Verify affected SharePoint Server versions
• Monitor SharePoint Server for suspicious activity

Evidence notes

The CVE Program record and NVD vulnerability detail provide information on the vulnerability. Microsoft has released a patch for this vulnerability. Affected versions include Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019, and Microsoft SharePoint Server Subscription Edition. The vulnerability exists due to improper access control in Microsoft Office SharePoint, allowing an authorized attacker to perform spoofing over a network. Evidence is based on CVE-

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.