CVE-2026-26110: Microsoft Office Remote Code Execution Vulnerability

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-10 · updated 2026-06-19
Weakness: CWE-843

Description

Access of resource using incompatible type ('type confusion') in Microsoft Office allows an unauthorized attacker to execute code locally.

Affected products

Microsoft 365 Apps: all versions
Microsoft 365 Copilot: before 16.0.19822.20000 — fixed in 16.0.19822.20000
Microsoft Office: 2016, 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 Office for Android: from 16.0.1 before 16.0.19822.20000 — fixed in 16.0.19822.20000
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 16.107.26030819 — fixed in 16.107.26030819
Microsoft Office: from 16.0.0 before 16.0.5543.1000 — fixed in 16.0.5543.1000
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 16.107.26030819 — fixed in 16.107.26030819

How to fix

Upgrade to a fixed version: Microsoft 365 Copilot 16.0.19822.20000; Microsoft 365 Apps https://aka.ms/OfficeSecurityReleases; Microsoft Office for Android 16.0.19822.20000; Microsoft Office LTSC 2021 https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC for Mac 2024 16.107.26030819; Microsoft Office 16.0.5543.1000; Microsoft Office LTSC 2024 https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC for Mac 2021 16.107.26030819. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26110

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