CVE-2026-62815: Microsoft Windows 11 23h2

Critical severity, CVSS 9.8. EPSS: 1% chance of exploitation in the next 30 days.

Use after free in Microsoft QUIC allows an unauthorized attacker to execute code over a network.

Affected products

• Microsoft Windows 11 23h2: before 10.0.22631.7517 (fixed in 10.0.22631.7517)
• Microsoft Windows 11 24h2: before 10.0.26100.9106 (fixed in 10.0.26100.9106)
• Microsoft Windows 11 25h2: before 10.0.26200.9106 (fixed in 10.0.26200.9106)
• Microsoft Windows 11 26h1: before 10.0.28000.2704 (fixed in 10.0.28000.2704)
• Microsoft Windows Server 2022: before 10.0.20348.5440 (fixed in 10.0.20348.5440)
• Microsoft Windows Server 2025: before 10.0.26100.33222 (fixed in 10.0.26100.33222)

Published 2026-08-11. Last modified 2026-08-14.