CVE-2026-54121: Microsoft Windows 10 1607

High severity, CVSS 8.8. EPSS: 0.8% chance of exploitation in the next 30 days.

Improper authorization in Active Directory Certificate Services (AD CS) allows an authorized attacker to elevate privileges over a network.

Affected products

• Microsoft Windows 10 1607: before 10.0.14393.9339 (fixed in 10.0.14393.9339)
• Microsoft Windows 10 1809: before 10.0.17763.9020 (fixed in 10.0.17763.9020)
• Microsoft Windows Server 2012: affected versions not specified; version r2 only
• Microsoft Windows Server 2016: before 10.0.14393.9339 (fixed in 10.0.14393.9339)
• Microsoft Windows Server 2019: before 10.0.17763.9020 (fixed in 10.0.17763.9020)
• Microsoft Windows Server 2022: before 10.0.20348.5386 (fixed in 10.0.20348.5386)
• Microsoft Windows Server 2025: before 10.0.26100.33158 (fixed in 10.0.26100.33158)

Published 2026-07-14. Last modified 2026-07-21.