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If you’re running Copilot in production, you already know the uncomfortable truth:
AI doesn’t “leak” data.
Your tenant leaks data — and AI makes the leak feel intelligent.
CVE-2026-24307 | M365 Copilot Information Disclosure Vulnerability is not “just another CVE.”
It’s a live exam for every organization claiming to be Copilot-ready.
Microsoft is doing the right thing by disclosing and patching.
But here’s the part most teams miss:
The most dangerous version of this CVE is not “Copilot is broken.”
It’s: Copilot is working exactly as designed — on permissions you forgot you granted.
MSRC reference: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-24307
TL;DR (for busy leaders)
If Copilot can surface out-of-scope content, one of these is usually true:
- Your identity boundary is too wide (users, apps, devices, sessions)
- Your content boundary is too wide (SharePoint/OneDrive/Teams sprawl, broken inheritance, oversharing)
- Your policy boundary is too weak (Purview labeling/DLP not enforced where Copilot reads)
- Your telemetry boundary is too quiet (no “Copilot-sensitive” detections, no proof trail)
So your response should be simple and brutal:
Shrink what Copilot can see, prove what changed, and keep it from drifting back.
Why this CVE lands harder than most “Info Disclosure” issues
Copilot changes the risk shape:
- It turns permission mistakes into confident answers
- It compresses search + synthesis into a single user action
- It makes “I didn’t know that doc existed” irrelevant — because Copilot can find it for you
- It increases the chance that sensitive fragments get repeated into chats, emails, notes, tickets
This is why the real control plane isn’t “AI settings.”
It’s:
Identity → Permissions → Labels → Session Controls → Telemetry → Proof
The Rahsi Copilot Boundary Model (the only model that matters in production)
Think of Copilot as a high-speed retrieval engine sitting on top of:
1) Identity Plane (who is asking)
- Entra ID user risk, sign-in risk
- Device compliance (Intune)
- Conditional Access (CA) session conditions
- Privileged identity controls (PIM / role activation hygiene)
2) Content Plane (what exists)
- SharePoint sites, libraries, Teams-connected sites
- OneDrive sprawl
- External sharing links
- Old content with new access
- Broken inheritance and “Everyone except external users” accidents
3) Policy Plane (what’s allowed)
- Purview sensitivity labels
- DLP policies (M365 + Endpoint DLP where needed)
- Insider risk signals and comms compliance where applicable
- Information barriers (if relevant to your org structure)
4) Telemetry Plane (what you can prove)
- Unified Audit Log
- Purview activity
- Defender XDR signals
- Sentinel detections and hunting
- “Evidence-ready” proof pack for auditors and customers
If any one of those planes is weak, Copilot will feel unsafe — even if the CVE is patched.
What “good” looks like: Copilot-safe by design
A. Shrink the highest-risk exposure first (fast wins in hours, not weeks)
1) Kill overshared content at the source
- Find sites with “broad groups” and legacy sharing patterns
- Fix broken inheritance and accidental wide audiences
- Reduce “anyone with the link” exposures where business allows
2) Ring-fence crown-jewel locations
Create a simple tiering model:
- Tier 0: secrets, legal, HR, finance, identity ops
- Tier 1: customer data, contracts, regulated content
- Tier 2: normal collaboration
Then enforce:
- stricter membership
- stricter sharing
- stricter labeling requirements
3) Make external sharing a deliberate act
- Time-bound sharing links by default
- Require MFA for guests
- Apply CA for guest access (device + session constraints where possible)
B. Make Copilot obey your information protection truth
4) Sensitivity labels must be real, not decorative
Labels must drive:
- encryption or access restrictions (where needed)
- container labeling (SharePoint sites / Teams)
- user prompts and policy outcomes
5) DLP must match how Copilot is actually used
DLP should consider:
- copying sensitive outputs into chats
- pasting into tickets
- emailing summarized data out of protected contexts
The goal isn’t to block everything.
The goal is: prevent high-impact leakage paths while keeping collaboration fast.
C. Harden the session where Copilot answers are produced
6) Conditional Access is your “answer quality gate”
For high-risk contexts:
- require compliant device
- require phishing-resistant auth where feasible
- reduce session lifetime for risky scenarios
- apply step-up for sensitive access paths
If the session is weak, the answers become risky.
CVE Surge Mode (the one switch every tenant should have)
When a Copilot disclosure CVE drops, your tenant should visibly change behavior for a short period.
Your surge mode should do three things:
1) Tighten high-risk access
- stricter CA for Copilot-enabled workloads
- restrict unmanaged devices for sensitive sites
- reduce standing privileges for admins and content owners
2) Freeze permission expansion
- no new broad-access groups
- no new “open” sites or libraries
- no new high-privilege connectors or automations touching sensitive content
3) Capture proof while you move
- baseline snapshots (before)
- change evidence (during)
- validation evidence (after)
If you can’t show deltas, you didn’t really respond — you just forwarded an advisory.
The Proof-Pack (what auditors and customers actually want)
When someone asks, “Are we safe from CVE-2026-24307?”
Your best answer is not a paragraph.
It’s a one-pack story:
- Scope: where Copilot is enabled
- Exposure: top oversharing fixes performed
- Policy: labeling + DLP enforcement posture
- Identity: CA posture + device compliance requirements
- Telemetry: detections + hunting queries
- Validation: spot checks + post-change confirmation
The win condition is simple:
You can explain your Copilot boundary in one page — and defend it in one hour.
The calm truth (and why Microsoft will respect this approach)
This is pro-Microsoft, because it’s how the platform is meant to be run:
- Microsoft gives you identity controls (Entra + CA)
- Microsoft gives you device truth (Intune)
- Microsoft gives you information protection (Purview)
- Microsoft gives you detection (Defender + Sentinel)
CVE-2026-24307 is the moment you connect them into one control plane.
Not fear. Not drama.
Just clean architecture.
If you want the “done-for-you” version
If you want, I can help you implement a full Copilot Boundary Blueprint:
- tenant-wide exposure map
- crown-jewel containment lanes
- CA + device posture gates
- Purview label/DLP alignment
- Sentinel detections + a proof-pack that survives audit season
If you’re building Copilot for real, you don’t need more content.
You need control.
— Aakash Rahsi
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