Data Protection Issues

Understanding Microsoft Graph Calendars.ReadWrite Access Permissions

Maira Mehtab Sep 21, 2026 869 views

Question details

The organization needs to clarify the extent of access granted by the Microsoft Graph Calendars.ReadWrite application permission.

Product: Microsoft Graph API
Device & OS: not provided
Scenario: Evaluating third-party app permissions for organizational calendar access to ensure data security.
Observed behavior: The organization wants to confirm whether the application can access full calendar event details or only free/busy information without a signed-in user.

Before you start

Ensure you have global administrator or privileged role administrator rights in your Microsoft 365 tenant to review and manage Azure AD application permissions.

Solution 1Recommended

Review Permissions and Audit Application Activity

Confirm the scope of the Calendars.ReadWrite permission and monitor the third-party application's calendar access via compliance logs.

The Microsoft Graph Calendars.ReadWrite application permission allows a third-party app to create, read, update, and delete events in all organization calendars without a signed-in user. This grants the app access to full calendar event details, not merely free/busy information.

Review granted permissions

Navigate to the Microsoft Entra ID (formerly Azure Active Directory) portal, go to 'Enterprise applications', and select the third-party app to review its granted API permissions.

Scope access if necessary

If full organizational access is not required, consider using Application Access Policies in Exchange Online to restrict the app's access to specific mailboxes.

Monitor audit logs

Access the Microsoft 365 Purview compliance portal and search the audit logs for application activity to verify exactly what calendar data the app is accessing and modifying.

Limited Sharing Alternatives: Consider utilizing limited calendar sharing or delegating permissions with lesser privileges if the third-party application only requires free/busy status.

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Frequently Asked Questions

Can Calendars.ReadWrite access private calendar events?

Yes, application permissions like Calendars.ReadWrite grant full administrative-level access to all events in the specified mailboxes, including those marked as private by the user.

How can I restrict this permission to specific users only?

You can use Microsoft Exchange Application Access Policies (via the New-ApplicationAccessPolicy PowerShell cmdlet) to restrict the app's calendar access to specific mailboxes or security groups.

Does Calendars.ReadWrite allow an app to send meeting invitations?

Yes, because the permission grants write access to calendars, the application can create events and subsequently trigger meeting invitations to attendees on behalf of the mailbox owner.

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