Heap-based Buffer Overflow in Microsoft Excel by Microsoft
CVE-2026-56156

7.8HIGH

Key Information:

Vendor

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

What is CVE-2026-56156?

A heap-based buffer overflow exists in Microsoft Excel that allows an unauthorized attacker to execute arbitrary code. This vulnerability can be exploited when a user opens a specially crafted Excel file, potentially compromising the security of the affected system. It is important for users to apply the necessary patches to protect against this risk and ensure the integrity of their data.

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 2021 32-bit Systems 16.0.1

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

.