Microsoft patches Excel RCE CVE-2026-81389 in Office for Mac

What happened

Microsoft published security updates for Microsoft Office for Mac that address CVE-2026-81389, a remote code execution vulnerability in Microsoft Excel. The update is targeted at affected Mac Office software; Microsoft says customers running other Microsoft Office software do not need to take action.

Impact

The vulnerability is described as an Excel remote code execution issue. If exploited, an attacker could run code in the context of the user opening a malicious Excel file. The source material does not provide affected versions, exploit status, severity score, or proof-of-concept details, so treat the vendor update as the primary control.

What to do

• Install the Microsoft Office for Mac security update on affected Macs, prioritizing systems where users open Excel files from email, web, or shared locations.
• Confirm patch status through endpoint management and verify that Excel is updated to the patched build.
• Apply standard Office RCE hygiene: restrict or review macros, block untrusted Office files in email gateways, and use sandboxing or application control where available.
• Monitor for suspicious Office process behavior, child processes, and network connections from Excel, and preserve forensic artifacts if compromise is suspected.

Because the public material is limited, do not assume the issue is unexploitable; patch affected Mac Office deployments and keep existing Office file handling controls in place.