CVE-2026-97773

Summary

A heap-based buffer overflow in Microsoft Excel allows remote attackers to execute arbitrary code when processing malicious Excel files. This vulnerability affects multiple Microsoft 365 and Office versions, making it a significant risk for enterprise environments.

Exploitability

Exploitation requires user interaction via a malicious Excel file delivered over the network, with no preconditions for successful exploitation once the file is opened.

Blast radius

If exploited, this vulnerability could allow attackers to gain full control of affected systems through Excel's auto-execution capabilities, potentially leading to widespread compromise across an organization.

Detection

No reliable host or network indicator is derivable from the published description.

Prioritized remediation

Deploy Microsoft Security Update MS26-078 for Office 2021, Office 2024, and Microsoft 365 apps, which addresses this heap-based buffer overflow vulnerability.

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