CVE-2025-54899: Microsoft Excel Remote Code Execution Vulnerability

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-09 · updated 2026-10-18
Weakness: CWE-590

Description

Free of memory not on the heap in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

Affected products

Microsoft 365 Apps: all versions
Microsoft Excel 2013 Service Pack 1: 2016
Microsoft Office: 2019
Microsoft Office LTSC for Mac 2021: 2021, 2024
Microsoft 365 Apps: from 16.0.1 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
Microsoft Excel 2016: from 16.0.0.0 before 16.0.5517.1000 — fixed in 16.0.5517.1000
Microsoft Office LTSC 2021: from 16.0.1 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC for Mac 2024: from 16.0.0 before 16.101.25091314 — fixed in 16.101.25091314
Microsoft Office: from 19.0.0 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2024: from 16.0.0 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC for Mac 2021: from 16.0.1 before 16.101.25091314 — fixed in 16.101.25091314

How to fix

Upgrade to a fixed version: Microsoft 365 Apps https://aka.ms/OfficeSecurityReleases; Microsoft Excel 2016 16.0.5517.1000; Microsoft Office LTSC 2021 https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC for Mac 2024 16.101.25091314; Microsoft Office https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC 2024 https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC for Mac 2021 16.101.25091314. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-54899

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