Oversharing is one of the most pervasive governance issues in Microsoft 365, and its impact becomes significantly amplified when Copilot is introduced. Copilot does not apply judgment to determine whether access is appropriate. It simply operates within the user’s existing Microsoft 365 permissions. If a user can view a document, Copilot can summarize, interpret, or reference it as contextual data. This makes unintentional access exactly as dangerous as intentional access. Before Copilot begins interpreting content at scale, organizations must address oversharing throughout SharePoint Online and OneDrive for Business.
Oversharing is not a Microsoft 365 problem; it is a permission hygiene problem.
Years of organic collaboration, rushed sharing decisions, inherited permissions, and abandoned sites create a landscape where many users can access far more content than intended.
How Oversharing Directly Impacts Copilot
Copilot’s behavior is governed entirely by the user’s access rights. This means oversharing not only exposes content; it also expands what Copilot can see and process. If a broad “Everyone” permission exists on a site, Copilot can summarize that content for every user in the organization.
Oversharing introduces risk in several forms:
- Legacy “Everyone except external users” permissions
- Unrestricted link types allowing broad internal visibility
- Unmanaged SharePoint site growth without governance
- Folder-level unique permissions that accumulate over the years
- Orphaned sites without responsible owners
- Personal OneDrive files are shared far more widely than intended
- External guest access that was never revoked
From Copilot’s perspective, all of this is legitimate access.
Fixing oversharing is not about restricting AI; it is about correcting the underlying permissions Copilot relies on.
Map and Analyze Current Sharing Across the Tenant
Before remediation begins, you need visibility into where sharing risk exists. Discovery should be both technical and behavioral. Microsoft provides several tools that help map your current exposure.
SharePoint and OneDrive can be assessed using:
- SharePoint Admin Center: Built-in external sharing and link visibility reports
- Microsoft Purview: Access Reviews for group membership auditing
- Graph API or PowerShell: Enumeration of unique permissions, link types, and inheritance breaks
- Secure Score insights: Recommendations on anonymous links, sharing patterns, and risk posture
The objective is to create a picture of the tenant’s current sharing state. In particular, focus on:
- Sites with large visitor groups
- Sites with many unique permissions
- Files shared externally or anonymously
- OneDrive folders shared with entire departments or the entire organization
- Sites with no assigned owners
- Sites that have not been accessed for long periods
This visibility allows you to prioritize remediation based on risk and impact.
Remove Overshared Links and Transition to Intent-Based Access
Sharing links often results in the most significant oversharing footprint, especially in environments where users frequently collaborate across teams. When you create a sharing link in SharePoint or OneDrive, the link type determines who can access it once the link is redeemed. Copilot acts on the permissions of the user who has redeemed (clicked) the link; it does not have a separate “sharing intelligence.”
What matters is whether a user can open the content; if so, Copilot can process it. Creating a link does not automatically expose content to Copilot; it becomes visible only when a user redeems the link and gains access.
Below is a table summarizing common link types and their impact on Copilot access:
Link Types and Resulting Copilot Access
| Link Type | Who Gets Access When Redeemed | Risk Level | Copilot Impact (Post-Redemption) |
|---|---|---|---|
| Anyone with the link | Anyone (authenticated or not, depending on external sharing settings) who has the URL and redeems it | Very High | Copilot may process the content if a valid M365 user opens it. |
| People in your organization | Any authenticated member of the tenant who redeems the link | High | Copilot may surface or summarize the file for any internal user who redeems and accesses it. |
| Specific people | Only the explicitly named, authenticated individuals | Very Low | Copilot can only process the content for those specific individuals who have redeemed access. |
| People with existing access | Only users who already had permissions — no new access granted | Low | Copilot behavior remains as before; no expansion of visibility. |
Disclaimer: These link behaviors are based on Microsoft’s official documentation for SharePoint and OneDrive shareable link types and the documented requirement that content must be redeemed (i.e., the link clicked and permissions granted) before it becomes accessible. Copilot does not gain access when a link is generated; it only does so after a user legitimately redeems the link and obtains permissions. As with all permission-based features, organizations should test their configuration to verify that link redemption and permission enforcement behave as expected in their environment (2025).
Here’s how each link type translates into Copilot behavior once redeemed by a user:
- Anyone with the link
This link requires no authentication. Once someone clicks the link, they immediately have access. If that person is an internal user who also logs into Microsoft 365 (or an external user, depending on sharing settings), Copilot will treat them as a valid user and can process any content they access via that link. Because the link is transferrable and not strictly tied to a user identity, this introduces a high risk: any recipient can redeem it, forward it, and grant Copilot access. - People in your organization
This link requires the user to be a member of your Microsoft 365 tenancy. Anyone in the organization who redeems the link and authenticates will be granted the access it provides. Once redeemed by a valid user, Copilot will treat the user’s permission as legitimate, meaning the file becomes part of the user’s accessible content set, potentially enabling summarization or reference by Copilot for any tenant user who obtains the link and redeems it. - Specific people
This link is tightly scoped: only the explicitly named, authenticated recipients can use it. When they redeem the link, they obtain access. Copilot’s visibility is then limited to the specific users’ permissions — unlike prior link types, access does not expand when the link is forwarded (to internal or external recipients). This provides the tightest control over what Copilot can see. - People with existing access
This is not a “grant new access” link. It simply generates a link for users who already have legitimate permissions. Because it doesn’t expand or change permissions, Copilot’s access is the same as before the link was generated.
Creating a link alone does not make content automatically visible to Copilot.
The content becomes visible only when a user redeems the link, grants permission, and then accesses it. That user’s permissions, not the mere presence of the link, govern what Copilot can do. Remediation involves replacing broad links with more controlled alternatives. In practice, this means:
- Removing “Anyone” and “People in your organization” links
- Replacing them with Specific People links
- Encouraging the use of SharePoint or Teams-backed permissions rather than file-level links
- Applying expiration policies to prevent long-term link drift
This transition ensures that Copilot inherits a much narrower, intentional access range.
Repair Site and Library Permissions at Scale
Oversharing frequently originates at the site or library level due to misaligned roles, unique permissions, and outdated structures. The goal is to return sites to predictable permission models.
Key tasks include:
- Restoring inheritance where it was previously broken
- Removing unnecessary unique permissions from libraries or folders
- Ensuring SharePoint groups (Owners, Members, Visitors) reflect real roles
- Replacing ad hoc access entries with Azure AD groups
- Validating site privacy settings (Private vs. Public) for Microsoft 365 Groups
- Assigning two or more site owners to maintain governance accountability
This step ensures the foundation of each site is healthy before applying AI governance.
Here is a simplified model of typical site roles:
Recommended SharePoint Role Model
| Role | Intended Audience | Microsoft Permission Level (Actual) |
|---|---|---|
| Owners | Individuals responsible for the site | Full Control |
| Members | Users who contribute content | Edit |
| Visitors | Users who consume content | Read |
Disclaimer: This role model is based on standard SharePoint Online permission levels documented by Microsoft. The described behaviors accurately reflect how permission levels govern user access and, by extension, Copilot’s visibility. Organizations using customized permission levels should validate their mappings to ensure Copilot access aligns with expected governance models.
Applying this structure universally reduces permission drift and makes Copilot’s access predictable.
Audit and Control OneDrive Sharing Behavior
OneDrive oversharing often goes unnoticed, yet it is one of Copilot’s most uncontrolled exposure surfaces. Users frequently store sensitive organizational documents in their personal OneDrive and share them widely for convenience.
Key remediation steps include:
- Identifying files shared using “Anyone” or “Organization-wide” links
- Limiting OneDrive external sharing at the user or tenant level
- Enforcing the sharing link expiration
- Automatically revoking old or unused sharing links
- Encouraging users to store team content in SharePoint instead of OneDrive
Because OneDrive behaves the same as SharePoint when Copilot is involved, reducing unnecessary OneDrive sharing significantly reduces unintended AI access.
Establish Governance Controls to Prevent Oversharing in the Future
Oversharing will return if not prevented by ongoing governance policies. After cleanup, long-term protection requires enforceable rules across collaboration, permissioning, and sharing.
Key governance controls include:
- Setting SharePoint and OneDrive default link types to Specific People
- Enforcing expiration dates for external shares
- Using Access Reviews to validate group membership regularly
- Applying Sensitivity Labels to SharePoint sites to enforce access boundaries
- Implementing Information Barriers where regulated separation is required
- Defining a standardized site provisioning model to prevent ownerless or misconfigured sites
Good governance creates a predictable access surface, which is essential for predictable AI behavior.
Validate Copilot Access After Remediation
Final validation ensures that your cleanup work is effective and that Copilot cannot access content that should now be restricted. Validation should be performed by both IT administrators and test users from different roles.
Recommended validation steps:
- Ask Copilot to summarize documents that were previously overshared
- Attempt to retrieve content across departments to validate new boundaries
- Confirm Copilot cannot reference content from removed or restricted locations
- Verify that Sensitivity Labels applied at the site level enforce expected access rules
- Validate that OneDrive files no longer appear where they should not
If Copilot still surfaces previously overshared content, additional remediation is required.
Closing Thoughts
Fixing oversharing in SharePoint and OneDrive is one of the most important steps in preparing your environment for Copilot. Copilot accelerates access; it does not validate whether that access is intentional. By reducing broad access links, correcting permission drift, enforcing least-privilege models, and applying governance controls, you create a secure environment where Copilot behaves predictably and safely.
Organizations that complete this step properly see a dramatic reduction in unintended data exposure risk once AI is enabled. Copilot becomes a trusted assistant, not a permission amplifier. In the next article, we will build on this foundation by addressing “Strengthen Conditional Access and Session Controls for Copilot Access“, where identity-driven protections become your next enforcement layer.