File Oversharing in 2026: Why Copilot and Gemini Surface Documents Nobody Meant to Share, What Everyone Links and Public Team Sites Actually Expose, and How to Audit Sharing Before You Switch On an AI Assistant
- Equipo de Internet Pros
- November 12, 2026
- Redes y Seguridad
Este artículo está disponible solo en inglés.
A new hire types “salary bands for the sales team” into the company AI assistant and gets a neat summary of a spreadsheet from HR. Nothing was hacked. The file sat in a site that had been open to the whole company since 2021, and nobody noticed because nobody went looking. Microsoft 365 Copilot and Gemini for Google Workspace do not break your permissions. They follow them exactly, and they are very good at finding things. In 2026 that has turned years of loose file sharing into one of the most common reasons AI rollouts get paused.
The Assistant Sees What the User Can See
Both assistants answer questions by searching the content the signed-in person already has access to: mail, chats, meeting notes, and files in SharePoint, OneDrive, Teams or Google Drive. If a file is readable by that person, it can show up in an answer. If it is not, it cannot. That rule sounds safe, and it is, as long as your permissions are right.
The trouble is that for most organisations they are not. Before AI, oversharing was protected by obscurity. A salary file shared with the whole company was technically visible to everyone, but you had to know which site to open and which folder to browse. An assistant removes the browsing. It turns “technically accessible” into “one question away”.
AI did not create your oversharing problem. It just started reading every file you forgot you had shared.
Where the Exposure Actually Comes From
Oversharing rarely comes from one bad decision. It builds up from defaults and shortcuts that seemed harmless at the time:
| Source | What it exposes | Why it is easy to miss |
|---|---|---|
| “Everyone except external users” permissions (Microsoft 365) | Every employee and every licensed account in the tenant | It was added to sites to “make access easy” and looks like a single harmless entry |
| Public Teams and Microsoft 365 groups | The whole team site and its files, to anyone in the organisation | “Public” is often the default when a team is created in a hurry |
| Organisation-wide Drive sharing (Google Workspace) | Files set to “anyone in your organisation”, sometimes searchable by all staff | It feels internal, so it feels safe |
| “Anyone with the link” sharing | Anyone holding the link, inside or outside the company, with no sign-in | Links get forwarded, pasted into tickets and never expire unless you set a limit |
| Broken inheritance and old groups | Folders shared with a departed contractor, a retired distribution list or a group that grew | Permissions set years ago are invisible until someone runs a report |
Two of these matter most for AI. Org-wide permissions are what the assistant searches for every employee, so they decide what a curious or careless user can surface. “Anyone” links matter more for leaks outside the company, but they are a strong signal that a site was never governed at all.
What the Platforms Give You to Find It
You do not need to read every folder. Both platforms now ship reports built for this exact problem:
- Microsoft 365: SharePoint Advanced Management, which Microsoft includes with Copilot licences, adds Data Access Governance reports. They list sites shared with “Everyone except external users”, sites with the most sharing links, and sites holding sensitive labelled content. Site access reviews then ask each site owner to confirm who should still have access.
- Microsoft 365 quick brakes: Restricted Content Discovery stops a chosen site from appearing in Copilot and organisation-wide search while you clean it up, without changing who can open the files directly. Sensitivity labels from Microsoft Purview can also block Copilot from using labelled content.
- Google Workspace: Admin console sharing settings control whether users can share outside the domain and what the default link setting is. The Drive audit log, and the security investigation tool on higher editions, show files shared externally or with the whole domain. Drive labels and data loss prevention rules can restrict sharing for sensitive files.
Treat these as a starting map, not a finished audit. They tell you where the wide doors are. Site owners still have to decide which ones should be closed.
A Pre-Rollout Oversharing Check
- Run the org-wide sharing report and sort by sites that also hold sensitive content: HR, finance, legal, payroll and executive files come first.
- Remove “Everyone” style permissions from those sites and replace them with named groups.
- Switch public teams that hold confidential work to private.
- Set the default sharing link to “specific people” and give “anyone” links an expiry date, or turn them off.
- Label your most sensitive files and block AI access to the highest labels.
- Use Restricted Content Discovery, or a pilot group, for sites you cannot fix before go-live.
- Test it: sign in as an ordinary employee and ask the assistant for salaries, contracts, passwords and board minutes. Fix whatever comes back.
Why a Ban Is Not the Answer
Some companies react by pausing the assistant indefinitely. That rarely holds. Staff who want AI help will paste the same files into a personal chatbot, which is a worse outcome. The real fix is the one you needed anyway: least-privilege access, with owners who review it. An assistant just makes the cost of skipping that work visible.
It also helps to roll out in waves. Start with teams whose content is already well governed, such as IT or marketing, and watch the questions people ask. Usage logs show which sites the assistant draws from most, which tells you where to clean up next.
Keep It Clean After Launch
Oversharing comes back. New teams get created, projects end, people change roles. Put three habits on the calendar: a quarterly org-wide sharing report, an annual access review for every site that holds sensitive data, and an offboarding step that removes a departing person from shared folders and groups, not just from sign-in. Each one is small. Skipping all three is how a 2021 salary sheet ends up in a 2026 chat answer.
En resumen
Copilot and Gemini respect your permissions exactly, which is the problem when those permissions grew loose over years of quick shares and default settings. An afternoon with the built-in sharing reports, a handful of permission fixes on your most sensitive sites, and a simple “ask it for salaries” test will remove most of the risk before anyone finds it the hard way.
Internet Pros helps businesses audit Microsoft 365 and Google Workspace sharing, fix permission sprawl and roll out AI assistants safely. Contáctanos to schedule an AI readiness review.
