CVE-2025-53809: Microsoft Windows 11 24h2

Medium severity, CVSS 6.5. EPSS: 1.5% chance of exploitation in the next 30 days.

Improper input validation in Windows Local Security Authority Subsystem Service (LSASS) allows an authorized attacker to deny service over a network.

Affected products

• Microsoft Windows 11 24h2: before 10.0.26100.6508 (fixed in 10.0.26100.6508)
• Microsoft Windows Server 2025: before 10.0.26100.6508 (fixed in 10.0.26100.6508)

Published 2025-09-09. Last modified 2026-06-17.