CVE-2026-56181: 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 10.0.26100.8875 (fixed in 10.0.26100.8875)
• Microsoft Windows 11 25h2: before 10.0.26200.8875 (fixed in 10.0.26200.8875)
• Microsoft Windows 11 26h1: before 10.0.28000.2525 (fixed in 10.0.28000.2525)
• Microsoft Windows Server 2025: before 10.0.26100.33158 (fixed in 10.0.26100.33158)

Published 2026-07-14. Last modified 2026-07-22.