CVE-2026-97778: Microsoft 365 Apps

High severity, CVSS 8.8. EPSS: 0.6% chance of exploitation in the next 30 days.

Integer overflow or wraparound in Microsoft Office Excel 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
• Microsoft Office Online Server: before 16.0.10417.20228 (fixed in 16.0.10417.20228)

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