CVE-2026-24307
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedImproper validation of specified type of input in M365 Copilot allows an unauthorized attacker to disclose information over a network.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceM365 Copilot contains an input validation flaw that allows unauthenticated attackers to disclose information over a network. The vulnerability stems from improper validation of a specific input type, enabling unauthorized data exposure.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE dataall versionsCVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Confirm M365 Copilot is enabled in your tenantReview Microsoft 365 admin center under 'Setup' or use Microsoft Graph/PowerShell to query Copilot license and usage statusAffected if M365 Copilot is active or provisioned in your organization
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Review Copilot data access permissionsCheck Microsoft 365 admin center for Copilot-specific data access policies and user permissions assigned to Copilot featuresAffected if Users have Copilot access enabled without proper input validation controls
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Audit network exposure of Copilot endpointsUse Microsoft Defender for Cloud Apps or network logs to identify exposed Copilot API endpoints accessible to unauthenticated actorsAffected if Copilot endpoints accept unauthenticated requests from external networks
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Check for unexpected data disclosure eventsReview Microsoft 365 audit logs (Unified Audit Log) for Copilot-related activities showing unauthorized data access or unusual information retrieval patternsAffected if Audit logs show data disclosure events initiated without proper authentication or input validation failures
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Verify input validation settings in Copilot promptsReview any configurable input filtering or prompt security settings in your M365 Copilot administration policiesAffected if Input validation is disabled or not enforced for Copilot interactions
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Confirm tenant-level authentication configurationCheck Microsoft 365 admin center security settings to ensure external users cannot access Copilot without authenticationAffected if Anonymous or guest access is permitted to Copilot-enabled services
Your organization is affected if M365 Copilot is enabled in your tenant and allows unauthenticated network access that could enable information disclosure through improper input validation.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataMonitor Microsoft security advisories for patches to M365 Copilot; implement network segmentation and least-privilege access controls as compensating controls until Microsoft releases an official fix.
- Consultation4.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,912.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-24307 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-24307 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data