CVE-2025-53766: Microsoft 365 Copilot

Critical severity, CVSS 9.8. EPSS: 8% chance of exploitation in the next 30 days.

Heap-based buffer overflow in Windows GDI+ allows an unauthorized attacker to execute code over a network.

Affected products

• Microsoft 365 Copilot: before 16.0.19127.20000 (fixed in 16.0.19127.20000)
• Microsoft Office: before 16.0.14326.22618 (fixed in 16.0.14326.22618)
• Microsoft Windows 10 1507: before 10.0.10240.21100 (fixed in 10.0.10240.21100)
• Microsoft Windows 10 1607: before 10.0.14393.8330 (fixed in 10.0.14393.8330)
• Microsoft Windows 10 1809: before 10.0.17763.7678 (fixed in 10.0.17763.7678)
• Microsoft Windows 10 21h2: before 10.0.19044.6216 (fixed in 10.0.19044.6216)
• Microsoft Windows 10 22h2: before 10.0.19045.6216 (fixed in 10.0.19045.6216)
• Microsoft Windows 11 22h2: before 10.0.22621.5768 (fixed in 10.0.22621.5768)
• Microsoft Windows 11 23h2: before 10.0.22631.5768 (fixed in 10.0.22631.5768)
• Microsoft Windows 11 24h2: before 10.0.26100.4851 (fixed in 10.0.26100.4851)
• Microsoft Windows Server 2008: affected versions not specified; version r2 only
• Microsoft Windows Server 2012: affected versions not specified; version r2 only
• Microsoft Windows Server 2016: before 10.0.14393.8330 (fixed in 10.0.14393.8330)
• Microsoft Windows Server 2019: before 10.0.17763.7678 (fixed in 10.0.17763.7678)
• Microsoft Windows Server 2022: before 10.0.20348.3989 (fixed in 10.0.20348.3989)
• Microsoft Windows Server 2022 23h2: before 10.0.25398.1791 (fixed in 10.0.25398.1791)
• Microsoft Windows Server 2025: before 10.0.26100.4851 (fixed in 10.0.26100.4851)

Published 2025-08-12. Last modified 2026-06-17.