What’s Vulnerable › Vulnerabilities

CVE-2026-88109: Microsoft Office Click-To-Run Elevation of Privilege Vulnerability

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-13 · updated 2026-10-31
• Weakness: CWE-416

Description

Use after free in Microsoft Office Click-To-Run allows an authorized attacker to elevate privileges locally.

Affected products

• Microsoft 365 Apps: all versions
• Microsoft Office 2021: all versions
• Microsoft Office LTSC 2024: all versions
• 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 16.0.14334.20974 — fixed in 16.0.14334.20974
• Microsoft Office LTSC 2024: from 16.0.0 before 16.0.17932.21056 — fixed in 16.0.17932.21056

How to fix

Upgrade to a fixed version: Microsoft 365 Apps https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC 2021 16.0.14334.20974; Microsoft Office LTSC 2024 16.0.17932.21056. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-88109

Get alerted when CVE-2026-88109 or the next vulnerability affects your stack