CVE-2026-56179: Microsoft Windows 11 24h2

High severity, CVSS 8.3. EPSS: 0.3% chance of exploitation in the next 30 days.

Origin validation error in Windows Network Address Translation (NAT) allows an unauthorized attacker to perform spoofing over an adjacent network.

Affected products

• 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 2025: before 10.0.26100.33222 (fixed in 10.0.26100.33222)

Published 2026-08-11. Last modified 2026-08-13.