CVE-2026-81389 Advisory
Severity: HIGH (CVSS 7.0)
Affected Product:
- Microsoft Defender Business
Vulnerability Description: Heap-based buffer overflow in Microsoft Office Excel enables local code execution by an unauthorized attacker.
KEV Status: Not currently listed as exploited in the wild.
Remediation:
- Apply security updates from Microsoft via the MSRC Update Guide: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81389
- Prioritize deployment given HIGH severity rating and code execution capability.
Attack Vector: Local access required.