CVE-2026-100209

Summary

A use-after-free vulnerability in Microsoft Excel allows remote attackers to execute arbitrary code when a malicious file is opened. This occurs when the application frees memory that is still being referenced, potentially leading to memory corruption and code execution.

Exploitability

Exploitation requires a user to open a specially crafted Excel file, making it moderately difficult but achievable through social engineering or phishing campaigns.

Blast radius

If exploited, this vulnerability could allow attackers to execute code on affected systems with the privileges of the user who opened the malicious file, potentially leading to full system compromise.

Detection

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

Prioritized remediation

Deploy Microsoft Security Update KB5041234 for Excel 2021 and Office 2024, or upgrade to Microsoft 365 version 2408 or later.

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