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High8.8Microsoft Server Exploited CISA KEV

High [CVE-2026-45659] Microsoft SharePoint Remote Code Execution Vulnerability

This high-severity Microsoft Server advisory covers CVE-2026-45659 affecting Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019, Microsoft SharePoint Server Subscription Edition.

CVE-2026-45659 Published May 22, 2026Updated by vendor Aug 10, 2026
Affected products & platforms
Microsoft ServerSharePoint Server
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Summary

Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.

Affected products named by the advisory: Microsoft SharePoint Enterprise Server 2016; Microsoft SharePoint Server 2019; Microsoft SharePoint Server Subscription Edition.

CISA Known Exploited Vulnerability

Listed:
Jul 1, 2026 · federal remediation due Jul 4, 2026
Required action:
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Ransomware use:
Known

KEV is a prioritization signal from CISA — remediation detail still comes from the vendor advisory.

Affected versions
  • Microsoft SharePoint Enterprise Server 2016 16.0.0 before 16.0.5552.1002
  • Microsoft SharePoint Server 2019 16.0.0 before 16.0.10417.20128
  • Microsoft SharePoint Server Subscription Edition 16.0.0 before 16.0.19725.20280

Official advisory · high-confidence parse· fetched 2 hours ago·verify at source

Fixed versions
  • 16.0.5552.1002
  • 16.0.10417.20128
  • 16.0.19725.20280

Official advisory · high-confidence parse· fetched 2 hours ago·verify at source

Mitigation

Upgrade to a fixed release: 16.0.5552.1002, 16.0.10417.20128, 16.0.19725.20280. That is the remediation for this advisory.

The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.

Official advisory · high-confidence parse· fetched 2 hours ago·verify at source

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