CVE-2021-40474

Code execution after opening crafted workbooks

Published Oct 13, 2021 · Updated Aug 4, 2024

Remote code execution in Microsoft Excel and Excel services allows attackers to run code when a crafted workbook is opened. Microsoft has not published the affected parser, file structure, or invalid operation that turns workbook input into code execution. Exploitation requires user interaction and runs code with the privileges of the affected application or document-processing service.

CVSS severity7.8
High
EPSS probability2.31%
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 Excel and Excel services allows attackers to run code when a crafted workbook is opened. Microsoft has not published the affected parser, file structure, or invalid operation that turns workbook input into code execution. Exploitation requires user interaction and runs code with the privileges of the affected application or document-processing service.

The record

CVE
CVE-2021-40474
Published
Oct 13, 2021
Updated
Aug 4, 2024
Vendor
Microsoft
Product
Microsoft Office 2019
Classifications
T1203, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=19.0.0 <https://aka.ms/OfficeSecurityReleases

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft Office 2019version=19.0.0 <https://aka.ms/OfficeSecurityReleases
Microsoft · Microsoft Excel 2016version=16.0.0.0 <16.0.5227.1000
Microsoft · Microsoft Office LTSC for Mac 2021version=16.0.1 <16.54.21101001
Microsoft · Microsoft Excel 2013version=15.0.0.0 <15.0.5389.1000
Microsoft · Microsoft Office 2019 for Macversion=16.0.0 <16.54.21101001
Microsoft · Microsoft Office LTSC 2021version=16.0.1 <https://aka.ms/OfficeSecurityReleases
Microsoft · Microsoft Office Online Serverversion=16.0.1 <16.0.10379.20000
Microsoft · Microsoft Office Web Apps Server 2013version=15.0.1 <15.0.5389.1000
Microsoft · Microsoft 365 Apps for enterpriseversion=16.0.1 <https://aka.ms/OfficeSecurityReleases

Published CVSS scores

6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
7.8Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:N/UI:R/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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1203Exploitation for Client Execution
T1204.002Malicious File

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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