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Actively exploited

CVE-2020-1147 Microsoft .NET Framework, SharePoint, and Visual Studio Remote Code Execution Vulnerability

Microsoft .NET Framework, Microsoft SharePoint, and Visual Studio contain a remote code execution vulnerability when the software fails to check the source markup of XML file input. Successful exploitation allows an attacker to execute code in the context of the process responsible for deserialization of the XML content.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch nowCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 3 Nov 2021.
  • Rated High severity (CVSS 7.8, scored by CISA).
  • This product type is often exposed to the internet, which is where attackers scan for it first.
  • It has been in the catalogue for 1,829 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

A remote code execution vulnerability exists in .NET Framework, Microsoft SharePoint, and Visual Studio when the software fails to check the source markup of XML file input, aka '.NET Framework, SharePoint Server, and Visual Studio Remote Code Execution Vulnerability'.

Affected Versions

ProductVersions
Microsoft Microsoft SharePoint Enterprise Server2016
2013 Service Pack 1
Microsoft Microsoft SharePoint Server2019
2010 Service Pack 2
Microsoft Microsoft Visual Studio 201916.0
Microsoft Microsoft Visual Studio 2019 version 16.6 (includes 16.0 - 16.5)unspecified
Microsoft Microsoft Visual Studio 2017 version 15.9 (includes 15.0 - 15.8)unspecified
Microsoft Microsoft Visual Studio 2019 version 16.4 (includes 16.0 - 16.3)unspecified

From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for Microsoft .NET Framework, SharePoint, Visual Studio. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply updates per vendor instructions.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated high, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 3 May 2022 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2020-1147
  3. CVE record: CVE-2020-1147
  4. FIRST EPSS
  5. portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1147
  6. packetstormsecurity.com/files/158694/SharePoint-DataSet-DataTable-Deserialization.html
  7. packetstormsecurity.com/files/158876/Microsoft-SharePoint-Server-2019-Remote-Code-Execution.html
  8. exploitalert.com/view-details.html?id=35992
  9. packetstormsecurity.com/files/163644/Microsoft-SharePoint-Server-2019-Remote-Code-Execution.html