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CVE-2021-40442: Microsoft Excel Remote Code Execution Vulnerability

• Severity: medium (CVSS 6.8 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-11-10 · updated 2026-08-19

Description

Microsoft Excel Remote Code Execution Vulnerability

Affected products

• Microsoft 365 Apps: all versions
• Microsoft Excel 2013 Service Pack 1: 2013-sp1, 2016
• Microsoft Office: 2019
• Microsoft Office LTSC for Mac 2021: 2021
• Microsoft Office Online Server: all versions
• Microsoft Office Web Apps Server: 2013-sp1
• Microsoft SharePoint Server: 2013-sp1
• Microsoft 365 Apps: from 16.0.1 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
• Microsoft Excel 2013 Service Pack 1: from 15.0.0.0 before 15.0.5397.1001 — fixed in 15.0.5397.1001
• Microsoft Excel 2016: from 16.0.0.0 before 16.0.5239.1001 — fixed in 16.0.5239.1001
• Microsoft Office 2019 for Mac: from 16.0.0 before 16.55.21111400 — fixed in 16.55.21111400
• Microsoft Office LTSC 2021: from 16.0.1 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
• Microsoft Office Web Apps Server 2013 Service Pack 1: from 15.0.1 before 15.0.5397.1001 — fixed in 15.0.5397.1001
• Microsoft SharePoint Enterprise Server 2013 Service Pack 1: from 15.0.0 before 15.0.5397.1001 — fixed in 15.0.5397.1001
• Microsoft Office: from 19.0.0 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
• Microsoft Office LTSC for Mac 2021: from 16.0.1 before 16.55.21111400 — fixed in 16.55.21111400
• Microsoft Office Online Server: from 16.0.1 before 16.0.10380.20000 — fixed in 16.0.10380.20000

How to fix

Upgrade to a fixed version: Microsoft 365 Apps https://aka.ms/OfficeSecurityReleases; Microsoft Excel 2013 Service Pack 1 15.0.5397.1001; Microsoft Excel 2016 16.0.5239.1001; Microsoft Office 2019 for Mac 16.55.21111400; Microsoft Office LTSC 2021 https://aka.ms/OfficeSecurityReleases; Microsoft Office Web Apps Server 2013 Service Pack 1 15.0.5397.1001; Microsoft SharePoint Enterprise Server 2013 Service Pack 1 15.0.5397.1001; Microsoft Office https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC for Mac 2021 16.55.21111400; Microsoft Office Online Server 16.0.10380.20000. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-40442
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40442

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