EUVD-2026-37946
GHSA-9cqp-hgpj-49wr
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Network-reachable function with missing authentication (PR:N, AC:L, UI:N) yields high confidentiality disclosure only, with no integrity or availability impact.
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
7DescriptionNVD
Missing authentication for critical function in M365 Copilot allows an unauthorized attacker to disclose information over a network.
AnalysisAI
Information disclosure in Microsoft 365 Copilot lets a remote, unauthenticated attacker reach a security-critical function that lacks an authentication check, exposing confidential data over the network. Classified CWE-306 (Missing Authentication for Critical Function) and rated CVSS 7.5, the flaw was reported by Microsoft and a vendor patch is available; there is no public exploit identified at time of analysis, though CISA's SSVC framework flags the issue as automatable with total technical impact. EPSS probability is low (0.50%, 39th percentile), indicating no current evidence of widespread exploitation.
Technical ContextAI
Microsoft 365 Copilot is the cloud-hosted generative-AI assistant embedded across the Microsoft 365 suite (Word, Excel, Outlook, Teams, etc.), grounded in tenant data via the Microsoft Graph. The root cause is CWE-306, Missing Authentication for Critical Function: a network-reachable function that performs or returns sensitive operations does not verify the caller's identity before acting, so the access-control gate that should precede data retrieval is absent or bypassable. The single CPE in scope, cpe:2.3:a:microsoft:microsoft_365_copilot:*, identifies the affected component as the Copilot service itself rather than a specific on-prem product version; because Copilot is a continuously-updated SaaS offering, the fix is delivered service-side by Microsoft rather than as a downloadable build.
RemediationAI
Patch available per vendor advisory: Microsoft has released a fix for CVE-2026-54130, documented at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54130. Because Microsoft 365 Copilot is a Microsoft-operated cloud service, remediation is applied service-side by the vendor and generally requires no customer-installed update; administrators should review the MSRC update guide to confirm the fix is active for their tenant and check whether any tenant-level configuration or acknowledgement is required. As compensating measures while confirming rollout, restrict Copilot availability to only the user populations that require it via Microsoft 365 admin and licensing controls (trade-off: reduces productivity for disabled users), tighten Graph/data-access scoping and sensitivity labels so that any data Copilot can surface is minimized (trade-off: may limit Copilot answer quality), and monitor Copilot and Graph audit logs for anomalous or unauthenticated-pattern access. Corroborate details against https://nvd.nist.gov/vuln/detail/CVE-2026-54130.
More in Microsoft 365 Copilot
View allInformation disclosure in Microsoft 365 Copilot allows remote unauthenticated attackers to exfiltrate data via command i
Remote code execution in Microsoft 365 Copilot allows an authenticated attacker to run arbitrary code over the network b
Privilege elevation in Microsoft 365 Copilot arises from an open redirect (CWE-601) that lets an unauthenticated remote
Privilege elevation in Microsoft 365 Copilot via an open redirect (CWE-601) lets an unauthenticated remote attacker abus
Command injection in Microsoft 365 Copilot allows an authenticated attacker with low privileges to execute arbitrary cod
Information disclosure in Microsoft 365 Copilot lets an unauthorized remote attacker inject specially crafted command el
Same technique Authentication Bypass
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External POC / Exploit Code
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