Introduction
Microsoft Excel, a cornerstone of productivity software, faces a critical security threat with CVE-2025-32704—a buffer over-read vulnerability enabling local attackers to execute arbitrary code. This flaw underscores the persistent challenges in securing widely-used applications and highlights the urgent need for immediate remediation.
Affected Systems and Versions
CVE-2025-32704 specifically impacts:
- Microsoft Office 2016 (all editions)
- Microsoft 365 Apps for Enterprise
- Excel for macOS (versions 16.75 and earlier)
These versions are vulnerable regardless of specific configuration, provided the attacker has local access to the system.
Technical Information
The vulnerability arises from improper memory handling within Excel, classified as a buffer over-read (CWE-126). Excel fails to adequately validate memory buffer boundaries when processing specially crafted files. This oversight allows attackers to read beyond the intended buffer limits, potentially executing arbitrary code within the context of the logged-in user.
Attackers exploit this flaw by creating malicious Excel files. When a user opens or previews these files, the vulnerability triggers, enabling code execution without further interaction. This attack vector is particularly dangerous as it bypasses typical user interaction requirements, significantly increasing the potential for stealthy exploitation.
Patch Information
Microsoft addressed this vulnerability in their May 2025 security update (KB5002695). Users and administrators should immediately apply this patch through Windows Update or enterprise management tools. For environments where immediate patching is not feasible, alternative mitigations include restricting local user privileges, implementing strict application whitelisting policies, and enhancing endpoint monitoring to detect unusual Excel activity.
Detection Methods
Currently, specific indicators of compromise or detailed detection methods have not been publicly disclosed. Organizations are encouraged to monitor Excel processes closely, particularly for unexpected memory allocation patterns or anomalous file interactions. Endpoint detection and response (EDR) solutions can help identify and mitigate potential exploitation attempts.
Vendor Security History
Microsoft has a mixed security history, marked by both proactive vulnerability management and occasional delays in addressing critical issues. Their prompt response to CVE-2025-32704, however, demonstrates a commitment to improving security practices, particularly for widely-used applications like Excel.
References
Organizations should prioritize patching and remain vigilant against potential exploitation attempts, ensuring robust defenses against this and similar vulnerabilities.
