CVE-2020-1023Network attack vector

Remote code execution via unchecked package markup

Published May 21, 2020 · Updated Aug 19, 2026

Remote code execution in Microsoft SharePoint 2013, 2016, and 2019 allows remote authenticated users to run arbitrary code via uploaded application packages. SharePoint fails to validate the source markup of an application package before processing it, allowing attacker-controlled content to reach server-side execution in the application pool and farm-account context. Exploitation requires a user with permission to upload the specially crafted package; successful attacks can compromise confidentiality, integrity, and availability of the server.

CVSS severity8.8
High
EPSS probability3.72%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Remote code execution in Microsoft SharePoint 2013, 2016, and 2019 allows remote authenticated users to run arbitrary code via uploaded application packages. SharePoint fails to validate the source markup of an application package before processing it, allowing attacker-controlled content to reach server-side execution in the application pool and farm-account context. Exploitation requires a user with permission to upload the specially crafted package; successful attacks can compromise confidentiality, integrity, and availability of the server.

The record

CVE
CVE-2020-1023
Published
May 21, 2020
Updated
Aug 19, 2026
Vendor
Microsoft
Product
Microsoft SharePoint Foundation 2013
Classifications
CWE-434, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=15.0.0 <publication

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft · Microsoft SharePoint Foundation 2013version=15.0.0 <publication
Microsoft · Microsoft SharePoint Enterprise Server 2016version=16.0.0 <publication
Microsoft · Microsoft SharePoint Server 2019version=16.0.0 <publication

Published CVSS scores

6.5NVDAV:N/AC:L/Au:S/C:P/I:P/A:P
8.8NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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