CVE-2021-24070

Remote code execution via crafted Excel file

Published Feb 25, 2021 · Updated Aug 3, 2024

Remote code execution in Microsoft Excel 2010 through 2019 and Microsoft 365 Apps allows remote attackers to execute code via a crafted file. Excel's XLS parser mishandles specially crafted record data, corrupting memory and enabling code execution in the current user's context. Exploitation requires a user to open the malicious workbook, so impact is bounded by that interaction and the user's privileges.

CVSS severity7.8
High
EPSS probability2.48%
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 2010 through 2019 and Microsoft 365 Apps allows remote attackers to execute code via a crafted file. Excel's XLS parser mishandles specially crafted record data, corrupting memory and enabling code execution in the current user's context. Exploitation requires a user to open the malicious workbook, so impact is bounded by that interaction and the user's privileges.

The record

CVE
CVE-2021-24070
Published
Feb 25, 2021
Updated
Aug 3, 2024
Vendor
Microsoft
Product
Microsoft Office 2019
Classifications
T1566.001
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=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 <publication
Microsoft · Microsoft Excel 2010version=13.0.0.0 <publication
Microsoft · Microsoft Excel 2013version=15.0.0.0 <publication
Microsoft · Microsoft Office Web Apps Server 2013version=15.0.1 <publication
Microsoft · Office Online Serverversion=https://aka.ms/OfficeSecurityReleases <publication
Microsoft · Microsoft 365 Apps for enterpriseversion=16.0.1 <https://aka.ms/OfficeSecurityReleases

Published CVSS scores

7.8MicrosoftCVSS: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

T1566.001Spearphishing Attachment

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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