What is CVE-2026-56181?

CVE-2026-56181 is a high-severity vulnerability in Microsoft Windows 11 Version 24h2, classified under Origin Validation Error. CVSS score: 8.3/10. Published 2026-07-14.

How severe is CVE-2026-56181?

High severity. CVSS v3 base score is 8.3 out of 10.

Vulnerability in Microsoft Windows 11 Version 24h2

CVE-2026-56181

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

CVSS v3 metric

CVSS v3 base score 8.3 (High). Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.

Affected products

Microsoft Windows 11 Version 24h2 — versions 10.0.26100.0
Microsoft Windows 11 Version 25h2 — versions 10.0.26200.0
Microsoft Windows 11 Version 26h1 — versions 10.0.28000.0
Microsoft Windows Server 2025 — versions 10.0.26100.0
Microsoft Windows Server 2025 (Server Core Installation) — versions 10.0.26100.0

Weakness classification (CWE)

CWE-346 — Origin Validation Error

References

secure@microsoft.com (vendor-advisory, patch)

Frequently asked questions

What is CVE-2026-56181?: CVE-2026-56181 is a high-severity vulnerability in Microsoft Windows 11 Version 24h2, classified under Origin Validation Error. CVSS score: 8.3/10. Published 2026-07-14.
How severe is CVE-2026-56181?: High severity. CVSS v3 base score is 8.3 out of 10.