CVE-2026-78505: Microsoft Office Remote Code Execution Vulnerability

Published Sep 8, 2026
·
Updated

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code over a network.

Other sources

Microsoft Office Remote Code Execution Vulnerability

Microsoft

Affected Software

13 affected componentsFixes available
Microsoft Office LTSC for Mac 2024
Microsoft Office LTSC 2021 for 32-bit editions<16.0.14334.20906
16.0.14334.20906
Microsoft Office LTSC for Mac 2021<16.112.26083020
16.112.26083020
Microsoft Office 2016<16.0.5569.1000
16.0.5569.1000
Microsoft Office LTSC 2024 for 64-bit editions<16.0.17932.20976
16.0.17932.20976
Microsoft Office LTSC 2021 for 64-bit editions<16.0.14334.20906
16.0.14334.20906
Microsoft Office LTSC 2024 for 32-bit editions<16.0.17932.20976
16.0.17932.20976
Microsoft Office 2019 for 64-bit editions<16.0.10417.20207
16.0.10417.20207
Microsoft Office 2016<16.0.5569.1000
16.0.5569.1000
Microsoft 365 Apps for Enterprise<16.0.20326.20138
16.0.20326.20138
Microsoft Office 2019 for 32-bit editions<16.0.10417.20207
16.0.10417.20207
Microsoft 365 Apps for Enterprise<16.0.20326.20138
16.0.20326.20138
Microsoft Office 365 for Mac

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 16.0.14334.20906
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 16.0.5569.1000Patch KB5002916
  3. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 16.0.17932.20976
  4. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 16.112.26083020
  5. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 16.0.10417.20207
  6. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 16.0.20326.20138

Event History

Sep 8, 2026
CVE Published
via Microsoft·02:00 PM
Data Sourced
via Microsoft·02:00 PM
DescriptionSeverityWeaknessAffected Software
Updated
via Microsoft·02:00 PM
Affected Software
Updated
via Microsoft·02:00 PM
Description
CVE Published
via MITRE·05:13 PM
Data Sourced
via MITRE·05:13 PM
DescriptionSeverity

Frequently Asked Questions

1

Which Office products are listed as affected?

The affected software list includes Microsoft Office 2016, Microsoft 365 Apps for Enterprise, Office LTSC 2021 for 32-bit and 64-bit editions, Office LTSC 2024 for 32-bit and 64-bit editions, Office LTSC for Mac 2021, and Office LTSC for Mac 2024.

2

Does an attacker need credentials or elevated privileges to exploit this issue?

No privileges are required according to the CVSS vector. Exploitation is network-based and has low attack complexity, but it requires user interaction.

3

What is the expected security impact if exploitation succeeds?

The CVSS vector rates confidentiality, integrity, and availability impact as high. The vulnerability is rated high severity with a CVSS score of 8.8.

Contact

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