CVE-2026-41100
Published: 12 May 2026
Summary
CVE-2026-41100 is a medium-severity Improper Access Control (CWE-284) vulnerability in Microsoft 365 Copilot. Its CVSS base score is 4.4 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Impersonation (T1684.001); ranked at the 16.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
This vulnerability is AI-related — categorised as Enterprise AI Assistants; in the Privacy and Disclosure risk domain.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-29686
Vulnerability details
Improper access control in M365 Copilot allows an authorized attacker to perform spoofing locally.
- CWE(s)
AI Security AnalysisAI
- AI Category
- Enterprise AI Assistants
- Risk Domain
- Privacy and Disclosure
- OWASP Top 10 for LLMs 2025
- None mapped
- Classification Reason
- Matched keywords: m365 copilot
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Improper access control enabling local spoofing directly facilitates impersonation of users or content within M365 Copilot.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
The access control policy and procedures directly mandate and enforce proper access control mechanisms across the organization.
Device lock enforces restricted access until re-authentication, directly reducing unauthorized use of active sessions.
Supervision and review of access control activities directly detects and remediates improper access configurations or usages.
Explicitly identifying and documenting actions permitted without identification or authentication enforces proper access control boundaries by defining justified exceptions.
By automatically labeling outputs with security attributes, the control supports attribute-based enforcement and reduces exploitability of improper access control weaknesses.
Associating and retaining security attributes with data directly supports enforcement of access control decisions across storage, processing, and transmission.
Requiring prior authorization for each remote access type prevents improper access control over remote connections.
Requiring authorization of wireless access before allowing connections enforces proper access control for this access method.