CVE-2025-55234

Windows SMB Elevation of Privilege Vulnerability

State: Published
Severity: 8.8 High
Published: Sep 9, 2025
Updated: Feb 26, 2026
Reserved: Aug 11, 2025

Description

SMB Server might be susceptible to relay attacks depending on the configuration. An attacker who successfully exploited these vulnerabilities could perform relay attacks and make the users subject to elevation of privilege attacks. The SMB Server already supports mechanisms for hardening against relay attacks:

SMB Server signing SMB Server Extended Protection for Authentication (EPA)

Microsoft is releasing this CVE to provide customers with audit capabilities to help them to assess their environment and to identify any potential device or software incompatibility issues before deploying SMB Server hardening measures that protect against relay attacks. If you have not already enabled SMB Server hardening measures, we advise customers to take the following actions to be protected from these relay attacks:

Assess your environment by utilizing the audit capabilities that we are exposing in the September 2025 security updates. See Support for Audit Events to deploy SMB Server Hardening—SMB Server Signing & SMB Server EPA. Adopt appropriate SMB Server hardening measures.

Scores

CVSS	Score	Vector	Source
3.1	8.8 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C	microsoft

Weaknesses

CWE-287 Improper Authentication

Affected Products

Product	Versions
Windows 10 Version 1507Microsoft	10.0.10240.0 to before 10.0.10240.21128Affected
Windows 10 Version 1607Microsoft	10.0.14393.0 to before 10.0.14393.8422Affected
Windows 10 Version 1809Microsoft	10.0.17763.0 to before 10.0.17763.7792Affected
Windows 10 Version 21H2Microsoft	10.0.19044.0 to before 10.0.19044.6332Affected
Windows 10 Version 22H2Microsoft	10.0.19045.0 to before 10.0.19045.6332Affected
Windows 11 version 22H2Microsoft	10.0.22621.0 to before 10.0.22621.5909Affected
Windows 11 version 22H3Microsoft	10.0.22631.0 to before 10.0.22631.5909Affected
Windows 11 Version 23H2Microsoft	10.0.22631.0 to before 10.0.22631.5909Affected
Windows 11 Version 24H2Microsoft	10.0.26100.0 to before 10.0.26100.6584Affected
Windows Server 2008 R2 Service Pack 1Microsoft	6.1.7601.0 to before 6.1.7601.27929Affected
Windows Server 2008 R2 Service Pack 1 (Server Core installation)Microsoft	6.1.7601.0 to before 6.1.7601.27929Affected
Windows Server 2008 Service Pack 2Microsoft	6.0.6003.0 to before 6.0.6003.23529Affected
Windows Server 2008 Service Pack 2 (Server Core installation)Microsoft	6.0.6003.0 to before 6.0.6003.23529Affected
Windows Server 2012Microsoft	6.2.9200.0 to before 6.2.9200.25675Affected
Windows Server 2012 (Server Core installation)Microsoft	6.2.9200.0 to before 6.2.9200.25675Affected
Windows Server 2012 R2Microsoft	6.3.9600.0 to before 6.3.9600.22774Affected
Windows Server 2012 R2 (Server Core installation)Microsoft	6.3.9600.0 to before 6.3.9600.22774Affected
Windows Server 2016Microsoft	10.0.14393.0 to before 10.0.14393.8422Affected
Windows Server 2016 (Server Core installation)Microsoft	10.0.14393.0 to before 10.0.14393.8422Affected
Windows Server 2019Microsoft	10.0.17763.0 to before 10.0.17763.7792Affected
Windows Server 2019 (Server Core installation)Microsoft	10.0.17763.0 to before 10.0.17763.7792Affected
Windows Server 2022Microsoft	10.0.20348.0 to before 10.0.20348.4171Affected
Windows Server 2022, 23H2 Edition (Server Core installation)Microsoft	10.0.25398.0 to before 10.0.25398.1849Affected
Windows Server 2025Microsoft	10.0.26100.0 to before 10.0.26100.6584Affected
Windows Server 2025 (Server Core installation)Microsoft	10.0.26100.0 to before 10.0.26100.6584Affected

References

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