CVE-2026-24299: M365 Copilot Command Injection Vulnerability

CVE-2026-24299 Overview

CVE-2026-24299 is a command injection vulnerability in Microsoft 365 Copilot that allows an unauthorized attacker to disclose sensitive information over a network. The vulnerability stems from improper neutralization of special elements used in commands (CWE-77), enabling attackers to manipulate Copilot's processing of user inputs to extract confidential data.

Critical Impact

Unauthorized attackers can exploit this command injection flaw to access and disclose sensitive information from M365 Copilot environments without authentication, potentially exposing confidential business data, emails, documents, and other organizational assets processed by the AI assistant.

Affected Products

• Microsoft 365 Copilot

Discovery Timeline

• 2026-03-19 - CVE-2026-24299 published to NVD
• 2026-03-19 - Last updated in NVD database

Technical Details for CVE-2026-24299

Vulnerability Analysis

This command injection vulnerability exists within Microsoft 365 Copilot's input processing mechanisms. The flaw allows attackers to craft specially formatted inputs that bypass normal sanitization routines, enabling the injection of malicious command sequences. When processed by Copilot, these injected commands can lead to unauthorized information disclosure.

The vulnerability requires user interaction and operates over the network, though exploitation complexity is considered high. While integrity and availability are not affected, the confidentiality impact is significant, as successful exploitation can result in exposure of sensitive information that Copilot has access to within the Microsoft 365 environment.

Root Cause

The root cause is improper neutralization of special elements used in command construction (CWE-77). M365 Copilot fails to adequately sanitize or neutralize user-supplied input before incorporating it into commands or queries, allowing attackers to inject special characters or sequences that alter the intended command logic and force disclosure of information the attacker should not have access to.

Attack Vector

The attack is conducted over the network and requires some level of user interaction. An attacker would need to craft a malicious input containing command injection payloads and deliver it in a way that causes the target user's Copilot instance to process it. The injected commands can then manipulate Copilot's behavior to retrieve and expose sensitive data from the user's M365 environment.

The attack does not require prior authentication but does have high complexity requirements, suggesting that specific conditions or configurations may need to be present for successful exploitation. The vulnerability primarily affects confidentiality, with no direct impact on integrity or availability of the system.

Detection Methods for CVE-2026-24299

Indicators of Compromise

• Unusual or malformed queries being processed by M365 Copilot containing special characters or command sequences
• Unexpected data access patterns or information retrieval requests from Copilot sessions
• Anomalous Copilot activity logs showing requests for data outside normal user access patterns
• Reports from users of unexpected responses or data exposure during Copilot interactions

Detection Strategies

• Monitor M365 Copilot audit logs for suspicious input patterns containing potential injection sequences
• Implement behavioral analysis to detect anomalous information access patterns through Copilot
• Review unified audit logs in Microsoft 365 for unusual Copilot-related activities
• Deploy endpoint detection to identify indicators of attempted exploitation

Monitoring Recommendations

• Enable comprehensive logging for all M365 Copilot interactions within your tenant
• Configure alerts for unusual data access patterns or queries through Copilot services
• Regularly review Microsoft 365 security center for Copilot-related security events
• Implement Data Loss Prevention (DLP) policies to detect and alert on sensitive data exposure

How to Mitigate CVE-2026-24299

Immediate Actions Required

• Review the Microsoft CVE-2026-24299 Advisory for official guidance and patches
• Apply any available security updates from Microsoft for M365 Copilot
• Assess your organization's exposure by reviewing Copilot usage and deployment
• Consider temporarily restricting Copilot access to sensitive data sources until patches are applied

Patch Information

Microsoft has published an official security advisory for this vulnerability. Organizations should consult the Microsoft Security Response Center (MSRC) advisory for the latest patch information and remediation guidance. As M365 Copilot is a cloud-based service, Microsoft will deploy fixes server-side, but administrators should verify their tenants are updated and follow any additional configuration recommendations.

Workarounds

• Implement strict input validation and monitoring for Copilot interactions at the organizational level
• Limit Copilot access to highly sensitive data repositories until the vulnerability is fully remediated
• Educate users about the risk of interacting with potentially malicious content through Copilot
• Review and tighten Copilot's data access permissions using Microsoft 365 sensitivity labels and access controls

# Review M365 Copilot audit logs via PowerShell
# Connect to Exchange Online and search for Copilot activities
Connect-ExchangeOnline
Search-UnifiedAuditLog -StartDate (Get-Date).AddDays(-7) -EndDate (Get-Date) -RecordType CopilotInteraction -ResultSize 5000 | Export-Csv -Path "CopilotAuditLogs.csv" -NoTypeInformation