CVE-2026-77902

Summary

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

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 user workstations across Microsoft 365 apps and Office 2021/2024 installations, potentially leading to widespread system compromise.

Detection

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

Prioritized remediation

Deploy the Microsoft Office 2021 or Office 2024 update KB5042789 immediately to address this vulnerability.

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