Improper Access Control in Microsoft Office Click-To-Run
CVE-2026-40420

8.8HIGH

Key Information:

Vendor

Microsoft
Status
Microsoft 365 Apps For Enterprise
Microsoft Office 2019
Microsoft Office Ltsc 2021
Microsoft Office Ltsc 2024
Vendor
CVE Published:
12 May 2026

What is CVE-2026-40420?

An improper access control issue in Microsoft Office Click-To-Run enables an attacker with valid credentials to gain elevated privileges locally. This vulnerability can lead to unauthorized actions within the application, potentially compromising the system's integrity and data security. Users are recommended to apply patches as outlined by Microsoft to mitigate risks associated with this vulnerability.

Affected Version(s)

Microsoft 365 Apps for Enterprise 32-bit Systems 16.0.1

Microsoft Office 2019 32-bit Systems 19.0.0

Microsoft Office LTSC 2021 32-bit Systems 16.0.1

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE...
vendor-advisorypatch

CVSS V3.1

Score:
8.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.