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Critical MSRC-CVE-2026-78501 1 CVE

Microsoft 365 Copilot Business Chat Information Disclosure Vulnerability

Published Sep 17, 2026 · Updated Oct 13, 2026 · Revision 3

Vendor: Microsoft

Summary

Impact: Information Disclosure. Microsoft rating: Critical. Not known to be exploited. Customer action: Not required.

Details

Why are there no links to an update or instructions with steps that must be taken to protect from this vulnerability?
This vulnerability has already been fully mitigated by Microsoft. There is no action for users of this service to take. The purpose of this CVE is to provide further transparency.
Please see Toward greater transparency: Unveiling Cloud Service CVEs for more information.

Vulnerabilities 1

  • High 8.6
    CVE-2026-78501

    Microsoft 365 Copilot Business Chat Information Disclosure Vulnerability

    Improper neutralization of special elements used in a command ('command injection') in Microsoft 365 Copilot's Business Chat allows an unauthorized attacker to disclose information over a network.

    Microsoft Microsoft 365 Copilot's Business Chat

Revision history

  1. #3

    Updated the CVSS User Interaction metric from Required (UI:R) to None (UI:N). The CVSS base score has increased to 8.6. This is an informational change only. No customer action is required.

  2. #2

    Updated an acknowledgement. This is an informational change only.

  3. #1

    Information published.

References