# CVE-2026-41100: Microsoft M365 Copilot improper access control spoofing

Source: https://junglewise.ai/threats/cve-2026-41100-microsoft-m365-copilot-improper-access-control-spoofing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-12. Updated: 2026-05-16  
License: CC BY 4.0 with a link back

CVE-2026-41100 · Severity: medium · CVSS 4.4 · Published 2026-05-12

A security vulnerability exists in Microsoft 365 Copilot, the AI-powered productivity tool integrated into Microsoft Office applications. An attacker with existing local access to a system could exploit this flaw to impersonate other users or services. This could lead to unauthorized actions being performed under a false identity, potentially compromising the integrity of internal communications or data.

Technologies: [Microsoft 365 Copilot](https://junglewise.ai/threats/technologies/365-copilot). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-41100 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-41100 being exploited in the wild.

**How severe is CVE-2026-41100?** Medium severity, with a CVSS score of 4.4, published 12 May 2026.

**Which products and versions are affected?** Microsoft Copilot M365 Copilot.

**Is there a fix for CVE-2026-41100?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-41100 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-41100?** Check whether you run Microsoft 365 Copilot. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability classified as improper access control (CWE-284) exists within Microsoft 365 Copilot. The flaw allows an attacker who is already authenticated to the local system to perform spoofing attacks. With a CVSS vector of AV:L/AC:L/PR:L/UI:N, the attack requires local access and low privileges but no user interaction. Successful exploitation allows the attacker to compromise the integrity and confidentiality of the application's operations by masquerading as a legitimate entity. Microsoft has released information regarding this vulnerability via the MSRC Update Guide.

## Affected products

- Microsoft Copilot M365 Copilot

## Timeline

- 2026-05-12: disclosed
- 2026-05-12: advisory: Microsoft published the security advisory.

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-41100](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-41100)

## Related threats

- [Microsoft Graphics Component stack buffer overflow](https://junglewise.ai/threats/cve-2026-85881-stack-based-buffer-overflow-in-microsoft-graphics-component)
- [Microsoft M365 Copilot command injection privilege escalation](https://junglewise.ai/threats/cve-2026-85885-improper-neutralization-of-special-elements-used-in-a-command)
- [Microsoft 365 Copilot Business Chat command injection](https://junglewise.ai/threats/cve-2026-78501-microsoft-365-copilot-business-chat-command-injection)
- [Microsoft Copilot command injection in mobile applications](https://junglewise.ai/threats/cve-2026-48561-microsoft-copilot-command-injection-in-mobile-applications)
- [Microsoft M365 Copilot open redirect privilege escalation](https://junglewise.ai/threats/cve-2026-41106-microsoft-m365-copilot-open-redirect-privilege-escalation)