Microsoft Security Response CenterCVE-2026-65807

Microsoft Excel Remote Code Execution Vulnerability

Access of resource using incompatible type ('type confusion') in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.

Read the vendor bulletin Get alerts for Microsoft Office 365 for Mac

8.8CVSS out of 10High severity

Scope

What the vendor says is affected

Microsoft Office 365 for Mac
Office Online Server
Microsoft Office 2019 for 32-bit editions
Microsoft Office 2019 for 64-bit editions
Microsoft 365 Apps for Enterprise for 32-bit Systems
Microsoft 365 Apps for Enterprise for 64-bit Systems
Microsoft Office LTSC for Mac 2021
Microsoft Office LTSC 2021 for 64-bit editions
Microsoft Office LTSC 2021 for 32-bit editions
Microsoft Office LTSC 2024 for 32-bit editions
Microsoft Office LTSC 2024 for 64-bit editions
Microsoft Office LTSC for Mac 2024
Microsoft Excel 2016 (32-bit edition)
Microsoft Excel 2016 (64-bit edition)

Versions the vendor lists as fixed

16.112.26081010
16.0.10417.20175
https://aka.ms/OfficeSecurityReleases
16.0.5565.1001

Next step

What the vendor recommends

Release Notes Click to Run Install KB5002884. Install KB5002903.

Review the complete instructions on the vendor's site

Update history

What changed in later vendor updates

SecurityAlert records field-level changes from the point we begin following a bulletin. Earlier vendor changes may not have a field-by-field record.

Aug 20, 2026 at 7:00 PM UTC
- The vendor changed its remediation guidance.

Timeline

When this advisory changed

Aug 11, 2026 at 7:00 AM UTC
Published by Microsoft Security Response Center
The publication date reported by the vendor.
Aug 20, 2026 at 6:50 PM UTC
Added to SecurityAlert
We collected the advisory from the official source.
Sep 2, 2026 at 5:15 PM UTC
Confirmed at the source
Our collector saw this advisory during a later source check.

Vulnerabilities

CVEs named in this advisory

CVE-2026-65807View CVSS, KEV, EPSS, and threat context

Source

Start with the vendor's bulletin

SecurityAlert organizes the fields the vendor published. The original bulletin remains the source of record for affected versions, fixes, and later changes.

Vendor: Microsoft Security Response Center
Advisory ID: CVE-2026-65807
Last source check: Sep 13, 2026 at 2:40 AM UTC

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Your environment

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Test the update or mitigation through your normal change process.

Watch Microsoft Office 365 for Mac

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What the vendor says is affected

Versions the vendor lists as fixed

What the vendor recommends

What changed in later vendor updates

When this advisory changed

CVEs named in this advisory

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