CVE-2025-53787: Microsoft 365 Copilot Information Vulnerability

CVE-2025-53787 Overview

CVE-2025-53787 is an information disclosure vulnerability affecting Microsoft 365 Copilot Chat (BizChat). This vulnerability allows unauthorized actors to access sensitive information through the Copilot BizChat interface without requiring authentication or user interaction. The flaw stems from improper command handling (CWE-77) within the AI-powered chat functionality, potentially exposing confidential data processed by the Copilot service.

Critical Impact

Attackers can exploit this vulnerability remotely over the network to gain unauthorized access to sensitive information processed by Microsoft 365 Copilot Chat, potentially compromising confidential business communications and data.

Affected Products

• Microsoft 365 Copilot Chat

Discovery Timeline

• 2025-08-07 - CVE-2025-53787 published to NVD
• 2025-08-14 - Last updated in NVD database

Technical Details for CVE-2025-53787

Vulnerability Analysis

This information disclosure vulnerability in Microsoft 365 Copilot Chat enables attackers to extract sensitive information without requiring any privileges or user interaction. The vulnerability is classified under CWE-77 (Improper Neutralization of Special Elements used in a Command), suggesting that the Copilot BizChat component fails to properly sanitize or validate certain inputs before processing them, allowing attackers to manipulate commands in a way that discloses protected information.

The attack surface is network-accessible, meaning exploitation can occur remotely without physical access to target systems. The vulnerability exclusively impacts confidentiality—there is no effect on data integrity or system availability. Organizations using Microsoft 365 Copilot Chat for business communications should treat this vulnerability with urgency given the potential for sensitive data exposure.

Root Cause

The vulnerability originates from improper neutralization of special elements used in command processing within the Copilot BizChat feature. The application fails to adequately validate or sanitize input before incorporating it into commands, allowing specially crafted requests to bypass intended access controls and retrieve information that should be protected.

Attack Vector

The attack vector is network-based, requiring no authentication and no user interaction. An attacker can exploit this vulnerability by sending specially crafted requests to the Microsoft 365 Copilot Chat service. The low attack complexity means that exploitation does not require special conditions or sophisticated techniques—a straightforward attack path exists that can be reliably executed.

Due to the nature of this vulnerability, sensitive business information processed through Copilot Chat could be exposed to unauthorized parties. This may include confidential documents, email contents, meeting notes, and other organizational data that Copilot has access to analyze and summarize.

Detection Methods for CVE-2025-53787

Indicators of Compromise

• Unusual query patterns or anomalous requests to Microsoft 365 Copilot Chat endpoints
• Unexpected data access patterns in Microsoft 365 audit logs showing Copilot-related activity
• Large volumes of data being retrieved through Copilot interfaces from external or unusual sources

Detection Strategies

• Enable and monitor Microsoft 365 Unified Audit Logs for Copilot-related activities
• Configure alerts for unusual Copilot query patterns, especially those requesting bulk data or sensitive information categories
• Review Microsoft Defender for Cloud Apps policies to detect anomalous Copilot usage
• Implement data loss prevention (DLP) policies to monitor information flowing through Copilot interfaces

Monitoring Recommendations

• Continuously monitor Microsoft Secure Score recommendations related to Copilot security configurations
• Review Copilot access logs regularly for unexpected query sources or patterns
• Enable Microsoft Purview Audit to track Copilot interactions with sensitive data
• Configure alerting for Copilot queries originating from non-standard geographic locations

How to Mitigate CVE-2025-53787

Immediate Actions Required

• Review the Microsoft Security Update for the latest patch information and apply updates immediately
• Audit current Copilot Chat access permissions and restrict to essential users only
• Enable enhanced logging for Microsoft 365 Copilot services to detect potential exploitation attempts
• Review sensitivity labels and information barriers to limit Copilot access to sensitive data

Patch Information

Microsoft has released security guidance for this vulnerability. Organizations should consult the Microsoft Security Response Center advisory for specific remediation instructions and ensure their Microsoft 365 environment receives the latest service updates. As Microsoft 365 Copilot is a cloud service, updates are typically deployed automatically by Microsoft; however, administrators should verify their tenant configuration aligns with Microsoft's security recommendations.

Workarounds

• Temporarily restrict Microsoft 365 Copilot Chat access to trusted users while evaluating the security update
• Implement additional access controls using Conditional Access policies in Microsoft Entra ID
• Review and tighten Copilot's data access scope using sensitivity labels in Microsoft Purview
• Consider temporarily disabling Copilot Chat for handling highly sensitive business functions until patches are confirmed applied