CVE-2026-70254

Summary

A buffer over-read vulnerability in Microsoft Excel allows remote attackers to execute arbitrary code when opening malicious Excel files. This occurs due to improper bounds checking when processing certain file structures, potentially enabling attackers to gain full control of affected systems.

Exploitability

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

Blast radius

If exploited, this vulnerability could allow attackers to execute code on user workstations with the privileges of the logged-in user, potentially leading to full system compromise and data exfiltration across Microsoft 365 and Office applications.

Detection

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

Prioritized remediation

Deploy the Microsoft Excel update KB5041078 or later to address this vulnerability in affected Office versions.

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