CVE-2026-97757

Summary

A heap-based buffer overflow in Microsoft Office Excel allows remote attackers to execute arbitrary code when processing malicious Excel files over a network. This vulnerability could enable attackers to gain full control of affected systems.

Exploitability

Exploitation requires a user to open a malicious Excel file, making it moderately difficult but achievable through social engineering or phishing campaigns with minimal preconditions.

Blast radius

If exploited, this vulnerability could impact millions of users running Microsoft 365 apps, Office 2021, and Office 2024, potentially leading to widespread remote code execution across enterprise networks.

Detection

Monitor for unusual Excel process activity in Windows Event Logs, particularly Event ID 4688 for new process creation involving excel.exe with suspicious command-line parameters or file access patterns that indicate processing of external files.

Prioritized remediation

Deploy the Microsoft Security Update KB5045789 for Excel 2021 and Office 2024, or upgrade to Microsoft 365 Apps for enterprise version 2408 or later.

Analysis generated locally by garnet-coder (no data left the box). AI-assisted — verify against primary sources before acting.