CVE-2026-56179

Analyzed Analyzed - Analysis Complete

Windows NAT Spoofing Vulnerability

Publication date: 2026-08-11

Last updated on: 2026-08-13

Assigner: Microsoft Corporation

Description

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

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-08-11

Last Modified

2026-08-13

Generated

2026-09-01

AI Q&A

2026-08-12

EPSS Evaluated

2026-08-30

NVD

CVE-2026-56179

EUVD

EUVD-2026-56763

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	windows_11_24h2	to 10.0.26100.9106 (exc)
microsoft	windows_11_24h2	to 10.0.26100.9106 (exc)
microsoft	windows_11_26h1	to 10.0.28000.2704 (exc)
microsoft	windows_11_26h1	to 10.0.28000.2704 (exc)
microsoft	windows_11_25h2	to 10.0.26200.9106 (exc)
microsoft	windows_11_25h2	to 10.0.26200.9106 (exc)
microsoft	windows_server_2025	to 10.0.26100.33222 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-346	The product does not properly verify that the source of data or communication is valid.

Attack-Flow Graph

Executive Summary

This vulnerability is an origin validation error in Windows Network Address Translation (NAT). It allows an unauthorized attacker to perform spoofing over an adjacent network, potentially tricking systems into accepting malicious traffic as legitimate.

Detection Guidance

Detection requires monitoring network traffic for spoofed packets originating from adjacent networks. Use tools like Wireshark to capture and analyze NAT traffic for anomalies. Check Windows Event Logs for unusual network activity or failed connection attempts.

Impact Analysis

An attacker could exploit this to impersonate trusted systems or users, leading to unauthorized access, data breaches, or network manipulation. It may also enable man-in-the-middle attacks or bypass security controls.

Compliance Impact

This vulnerability could lead to unauthorized data access or exposure, violating confidentiality requirements in GDPR and HIPAA. Organizations may face compliance violations if exploited, resulting in penalties or legal consequences.

Mitigation Strategies

Apply the latest Windows security updates from Microsoft to patch the origin validation error in NAT. Monitor Microsoft's advisory for additional guidance.

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