Approximately 16.9% of Windows client devices are still using Windows 10, while Windows 11 accounts for 78.8% of installations. Windows 10's market share has significantly declined from nearly 50% in mid-2025. The migration to Windows 11 is slowing, with remaining Windows 10 devices facing more complex and costly upgrade scenarios, including having three times as many active Common Vulnerabilities and Exposures (CVEs) compared to Windows 11. Legacy operating systems like Windows 7, Windows 8.1, and Windows XP are also factors in the migration challenges. Microsoft’s Extended Security Updates (ESU) program offers protection until October 2027 for consumers and until October 2028 for commercial customers.