Heap-based Buffer Overflow in Microsoft Office OneNote
CVE-2026-55133

7.8HIGH

Key Information:

Vendor

Microsoft
Status
Microsoft 365 Apps For Enterprise
Microsoft Office 365 For Mac
Microsoft Office Ltsc For Mac 2021
Microsoft Office Ltsc For Mac 2024
Vendor
CVE Published:
14 July 2026

What is CVE-2026-55133?

A heap-based buffer overflow vulnerability in Microsoft Office OneNote could enable malicious actors to execute arbitrary code on affected systems. This flaw allows an unauthorized attacker to exploit the vulnerability by crafting and delivering a specially designed file, leading to local code execution. Users are encouraged to apply available patches to mitigate the risk associated with this serious security concern.

Affected Version(s)

Microsoft 365 Apps for Enterprise 32-bit Systems 16.0.1

Microsoft Office 365 for Mac 1.0.0 < 16.111.26071215

Microsoft Office LTSC for Mac 2021 16.0.1 < 16.111.26071215

References

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

CVSS V3.1

Score:
7.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.