Executive brief
Microsoft 365 Copilot, an AI-powered productivity tool, contains a critical security flaw that could allow an authorized user to execute unauthorized commands. An attacker with basic access to the service could potentially take full control of the environment, leading to significant data theft or service disruption. Because this is a cloud-based service, Microsoft typically manages the necessary updates to resolve the issue.
Technical details
A deserialization vulnerability (CWE-502) exists in Microsoft 365 Copilot due to the insecure handling of untrusted data. An attacker with low-privileged network access can exploit this flaw without any user interaction to achieve remote code execution. The vulnerability is particularly severe as it carries a 'Changed' Scope (S:C) in the CVSS metric, indicating that an exploit could impact components beyond the immediate security scope of the Copilot service. As an exclusively hosted service, remediation is primarily handled by Microsoft on the backend.
Affected products
- Microsoft Microsoft 365 Copilot All versions
Timeline
- 2026-07-24: disclosed: Initial advisory publication date
- 2026-07-24: advisory: Microsoft and NVD published vulnerability details