CVE-2026-45497: Microsoft M365 Copilot Remote Code Execution Vulnerability

Synopsis

A command injection vulnerability in Microsoft 365 Copilot allows an authenticated attacker to execute arbitrary code remotely by sending specially crafted input over the network. The exploit requires a low-privilege account and elevated attack complexity, but no victim interaction, and operates with a changed scope affecting systems beyond the directly targeted component. Successful exploitation gives an attacker the ability to run arbitrary commands, read sensitive data, and partially tamper with or disrupt the service. No fix version has been published yet; HarborGuard tracks this advisory and will make a patched-image rebuild available the moment upstream ships a fix.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must reach the Microsoft 365 Copilot service over the network; local or physical access is not sufficient.

• AuthenticationRequired

  A low-privilege authenticated account is sufficient; anonymous or unauthenticated access cannot trigger this vulnerability.

• Victim interactionNot required

  No user interaction is needed; the attacker can trigger the vulnerability entirely on their own without involving another user.

• Attack complexityDetail

  Attack complexity is high, meaning the attacker must account for environmental conditions or race-condition-style factors to reliably achieve exploitation.

Blast Radius

• A successful attacker executes arbitrary operating-system commands in the context of the Copilot service, with scope change meaning the impact can extend to systems beyond the directly targeted component.
• Confidentiality impact is high: the attacker reads sensitive data processed or stored by the service, which may include user prompts, organizational data, and session context.
• Integrity impact is partial: the attacker modifies a subset of data or service state, but does not necessarily gain full write control.
• Availability impact is partial: the attacker disrupts or degrades service operation without necessarily causing a complete denial of service.