What’s Vulnerable › Vulnerabilities
CVE-2021-38655: Microsoft Excel Remote Code Execution Vulnerability
- Severity: medium (CVSS 6.8 v2.0)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 6.4% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2021-09-15 · updated 2026-08-10
- Weakness: CWE-416
Description
Microsoft Excel Remote Code Execution Vulnerability
Affected products
- Microsoft 365 Apps: all versions
- Microsoft Excel 2013 Service Pack 1: 2013, 2013-sp1, 2016
- Microsoft Office: 2019
- Microsoft Office Online Server: all versions
- Microsoft Office Web Apps: 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 5381.1000 — fixed in 5381.1000
- Microsoft Excel 2016: from 16.0.0.0 before 5215.1000 — fixed in 5215.1000
- Microsoft Office 2019 for Mac: from 16.0.0 before 16.53.21091200 — fixed in 16.53.21091200
- Microsoft Office Web Apps Server 2013 Service Pack 1: from 15.0.1 before 5381.1000 — fixed in 5381.1000
- Microsoft Office: from 19.0.0 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
- Microsoft Office Online Server: from 16.0.1 before 10378.20000 — fixed in 10378.20000
How to fix
Upgrade to a fixed version: Microsoft 365 Apps https://aka.ms/OfficeSecurityReleases; Microsoft Excel 2013 Service Pack 1 5381.1000; Microsoft Excel 2016 5215.1000; Microsoft Office 2019 for Mac 16.53.21091200; Microsoft Office Web Apps Server 2013 Service Pack 1 5381.1000; Microsoft Office https://aka.ms/OfficeSecurityReleases; Microsoft Office Online Server 10378.20000. Check the vendor advisory for mitigations.
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-38655
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-38655
- https://www.zerodayinitiative.com/advisories/ZDI-21-1080/
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