CVE-2021-31939: Microsoft Excel Remote Code Execution Vulnerability

Severity: medium (CVSS 6.8 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 13.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-06-08 · updated 2026-06-17

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: 2013-sp1, 2016, 2019
Microsoft Office Online Server: all versions
Microsoft Office Web Apps 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 15.0.5353.1000 — fixed in 15.0.5353.1000
Microsoft Excel 2016: from 16.0.0.0 before 16.0.5173.1000 — fixed in 16.0.5173.1000
Microsoft Office 2013 Service Pack 1: from 15.0.0 before 15.0.5353.1000 — fixed in 15.0.5353.1000
Microsoft Office Web Apps Server 2013 Service Pack 1: from 15.0.1 before 15.0.5353.1000 — fixed in 15.0.5353.1000
Microsoft Office: from 19.0.0 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
Microsoft Office Online Server: from https://aka.ms/OfficeSecurityReleases before 16.0.10375.20000 — fixed in 16.0.10375.20000

How to fix

Upgrade to a fixed version: Microsoft 365 Apps https://aka.ms/OfficeSecurityReleases; Microsoft Excel 2013 Service Pack 1 15.0.5353.1000; Microsoft Excel 2016 16.0.5173.1000; Microsoft Office 2013 Service Pack 1 15.0.5353.1000; Microsoft Office Web Apps Server 2013 Service Pack 1 15.0.5353.1000; Microsoft Office https://aka.ms/OfficeSecurityReleases; Microsoft Office Online Server 16.0.10375.20000. Check the vendor advisory for mitigations.

References

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