Retirement of Microsoft 365 Companion apps

🚨 The Signal: Microsoft is retiring the M365 companion apps (Calendar, People, Files) by December 2026. These apps will no longer receive security updates, posing a risk if not removed. Admins must uninstall them from managed devices.

The Impact

Admins and users are affected by the need to remove unsupported applications, increasing the attack surface if unaddressed.

• Admins: Must remove unsupported apps from managed devices to prevent security vulnerabilities.
• Users: Must uninstall apps from unmanaged devices to avoid using unpatched software.
• Security Teams: Must verify removal to reduce the attack surface from unpatched applications.

The Action

1. Identify devices with Microsoft 365 companion apps installed.
2. Develop and deploy a plan to uninstall companion apps from all managed devices by December 16, 2026.
3. Communicate to users of unmanaged devices to uninstall the companion apps themselves.
4. Verify the removal of companion apps across the environment.

Domain: M365-Apps · Impact: medium · Workload: M365 Apps · Essential Eight: Patch Applications, User Application Hardening · ISM: ISM-0304, ISM-1412, ISM-1485, ISM-1486, ISM-1542, ISM-1585, ISM-1667, ISM-1668, ISM-1669, ISM-1670, ISM-1690, ISM-1691, ISM-1692, ISM-1693, ISM-1698, ISM-1699, ISM-1700, ISM-1704, ISM-1807, ISM-1808, ISM-1823, ISM-1824, ISM-1859, ISM-1860, ISM-1876, ISM-1901, ISM-1905