Out-of-Bounds Read Vulnerability in Microsoft Office Outlook
CVE-2026-78520

6.5MEDIUM

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-2026-78520?

A security flaw in Microsoft Office Outlook allows unauthorized users to read memory outside designated buffers. This vulnerability can be exploited to execute arbitrary code remotely over a network, posing a significant risk to system integrity and data confidentiality. It is crucial for users of affected Outlook versions to install the latest security updates to mitigate potential exploitation.

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:
6.5
Severity:
MEDIUM
Confidentiality:
High
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.