CVE-2021-43905: Microsoft 365 Copilot

Critical severity, CVSS 9.6. EPSS: 3% chance of exploitation in the next 30 days.

Microsoft Office app Remote Code Execution Vulnerability

Affected products

• Microsoft 365 Copilot: before 18.2110.13110.0 (fixed in 18.2110.13110.0)

Published 2021-12-15. Last modified 2026-06-17.