Heap-Based Buffer Overflow in Microsoft Office Word
CVE-2026-78517

8.8HIGH

Key Information:

Vendor

Microsoft
Status
Microsoft 365 Apps For Enterprise
Microsoft Office 2019
Microsoft Office 365 For Mac
Microsoft Office Ltsc 2021
Vendor
CVE Published:
8 September 2026

What is CVE-2026-78517?

A heap-based buffer overflow vulnerability in Microsoft Office Word has been identified, enabling potential unauthorized remote code execution. This critical flaw can be exploited by an attacker to execute arbitrary code over a network when a vulnerable version of the software processes a specially crafted document. It is essential to apply security patches promptly to mitigate the risks associated with this vulnerability.

Affected Version(s)

Microsoft 365 Apps for Enterprise 32-bit Systems 16.0.1 < 16.0.20326.20138

Microsoft Office 2019 32-bit Systems 19.0.0 < 16.0.10417.20207

Microsoft Office 365 for Mac -

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:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.