CVE-2025-59252 is a critical security vulnerability classified under CWE-77 (Improper Neutralization of Special Elements used in a Command, i.e., command injection) affecting Microsoft 365 Word Copilot. This vulnerability stems from the failure to properly sanitize or neutralize special characters or elements in commands processed by the Copilot feature, which is integrated into Microsoft Word within the Microsoft 365 suite. As a result, an unauthenticated attacker can craft malicious inputs that are interpreted as commands by the underlying system, leading to unauthorized command execution. The primary impact is the disclosure of sensitive information over the network, indicating that confidentiality is severely compromised. The CVSS v3.1 base score of 9.3 reflects the vulnerability's critical nature, with attack vector being network-based (AV:N), no privileges required (PR:N), no user interaction needed (UI:N), and scope changed (S:C), meaning the vulnerability affects resources beyond the initially vulnerable component. Integrity impact is low, and availability is unaffected. The vulnerability was reserved in September 2025 and published in October 2025, with no known exploits in the wild yet and no patches currently available. Given the integration of Copilot in Microsoft 365 Word, a widely used productivity tool, the attack surface is significant. The vulnerability could be exploited remotely without authentication or user interaction, making it highly dangerous. The improper neutralization of special elements likely involves failure to sanitize inputs that are passed to system commands or scripts, allowing injection of arbitrary commands. This could lead to attackers exfiltrating sensitive documents or data processed by Word Copilot, potentially impacting confidentiality of corporate or personal information.

For European organizations, the impact of CVE-2025-59252 is substantial due to the widespread adoption of Microsoft 365 services across enterprises, government agencies, and critical infrastructure. The vulnerability allows remote, unauthenticated attackers to disclose sensitive information, which could include confidential documents, intellectual property, or personal data protected under GDPR. This poses significant legal and financial risks, including regulatory fines and reputational damage. The partial integrity impact could allow attackers to manipulate some data or commands, potentially leading to further exploitation or lateral movement within networks. The lack of required privileges and user interaction lowers the barrier for exploitation, increasing the likelihood of attacks. Organizations in sectors such as finance, healthcare, government, and manufacturing are particularly at risk due to the sensitive nature of their data and the strategic value of their information. Additionally, the scope change indicates that the vulnerability could affect multiple components or systems beyond the immediate application, potentially amplifying the impact. The absence of patches at the time of disclosure necessitates immediate compensating controls to reduce exposure. Overall, the vulnerability threatens confidentiality and integrity of critical information assets in European organizations, with potential cascading effects on operational security and compliance.

1. Immediate Actions: Monitor official Microsoft security advisories closely and apply patches or updates for Microsoft 365 Word Copilot as soon as they are released. 2. Network Controls: Implement strict network segmentation and firewall rules to limit outbound connections from endpoints running Microsoft 365 Word Copilot, reducing the risk of data exfiltration. 3. Access Restrictions: Restrict usage of Word Copilot features to trusted users and devices, leveraging identity and access management policies to enforce least privilege. 4. Input Validation: Where possible, enforce additional input validation or sanitization on documents or macros that interact with Copilot to reduce injection vectors. 5. Monitoring and Detection: Deploy advanced endpoint detection and response (EDR) tools to identify anomalous command execution patterns or unusual network traffic originating from Microsoft Word processes. 6. User Awareness: Educate users about the risks of opening untrusted documents or enabling features that may invoke Copilot commands. 7. Incident Response Preparedness: Prepare incident response plans specific to potential exploitation of this vulnerability, including data exfiltration scenarios. 8. Alternative Workflows: Temporarily disable or limit Copilot functionality in sensitive environments until patches are available. 9. Logging and Auditing: Enable detailed logging of Microsoft 365 Word Copilot activities to facilitate forensic analysis if exploitation occurs. These measures go beyond generic advice by focusing on controlling the attack surface specific to Copilot’s command processing and network behavior.