Advisoriesby IbisMicrosoftCVE-2026-56181
Microsoft Windows: spoofing
Fix: upgrade to 10.0.26100.8875 or later (4 fixed versions below)
Origin validation error in Windows Network Address Translation (NAT) allows an unauthorized attacker to perform spoofing over an adjacent network.
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| Windows 11 Version 24H2 Product | >= 10.0.26100.0, < 10.0.26100.8875 | 10.0.26100.8875 |
| Windows 11 Version 25H2 Product | >= 10.0.26200.0, < 10.0.26200.8875 | 10.0.26200.8875 |
| Windows 11 version 26H1 Product | >= 10.0.28000.0, < 10.0.28000.2525 | 10.0.28000.2525 |
| Windows Server 2025 Product | >= 10.0.26100.0, < 10.0.26100.33158 | 10.0.26100.33158 |
| Windows Server 2025 (Server Core installation) Product | >= 10.0.26100.0, < 10.0.26100.33158 | 10.0.26100.33158 |
Details and references
- CVSS 3.1
- CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
- Severity from
- the vendor (its own CVE record or advisory)
- Weakness
- CWE-346