What’s Vulnerable › Vulnerabilities
CVE-2026-40366: Microsoft Word Remote Code Execution Vulnerability
- Severity: high (CVSS 8.4 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.4% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-05-12 · updated 2026-10-26
- Weakness: CWE-416
Description
Access of resource using incompatible type ('type confusion') in Microsoft Office Word allows an unauthorized attacker to execute code locally.
Affected products
- Microsoft 365 Apps: all versions
- Microsoft Office: 2019
- Microsoft Office LTSC for Mac 2021: 2021, 2024
- Microsoft Word for Android: 2016
- Microsoft 365 Apps: from 16.0.1 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
- 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 16.109.26051019 — fixed in 16.109.26051019
- Microsoft Word 2016: from 16.0.1 before 16.0.5552.1000 — fixed in 16.0.5552.1000
- 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 16.109.26051019 — fixed in 16.109.26051019
How to fix
Upgrade to a fixed version: Microsoft 365 Apps https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC 2021 https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC for Mac 2024 16.109.26051019; Microsoft Word 2016 16.0.5552.1000; Microsoft Office https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC 2024 https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC for Mac 2021 16.109.26051019. Check the vendor advisory for mitigations.
References
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