CVE-2026-88156: Microsoft 365 Apps

Critical severity, CVSS 9.8. EPSS: 1% chance of exploitation in the next 30 days.

Stack-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.

Affected products

• Microsoft 365 Apps: affected versions not specified
• Microsoft Microsoft 365: affected versions not specified
• Microsoft Office 2021: affected versions not specified
• Microsoft Office 2024: affected versions not specified

Published 2026-10-13. Last modified 2026-10-15.