CVE-2025-55234

Published Sep 9, 2025

Last updated 12 days ago

SMB Server

Overview

AI description

Automated description summarized from trusted sources.

CVE-2025-55234 is an elevation of privilege vulnerability affecting Windows Server Message Block (SMB). It exists because SMB sessions can be established without properly validating the authentication context when key hardening measures, such as SMB signing and extended protection for authentication (EPA), are not in place. An unauthenticated, remote attacker could perform relay attacks by exploiting improper authentication mechanisms in SMB Server configurations over a network connection. Successful exploitation could allow an attacker to elevate their privileges to that of the compromised user's account. Microsoft has released audit capabilities to help customers assess their environment and identify potential incompatibility issues before deploying SMB Server hardening measures.

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.
Source: secure@microsoft.com
NVD status: Analyzed
Products: windows_10_1507, windows_10_1607, windows_10_1809, windows_10_21h2, windows_10_22h2, windows_11_22h2, windows_11_23h2, windows_11_24h2, windows_server_2008, windows_server_2012, windows_server_2016, windows_server_2019, windows_server_2022, windows_server_2022_23h2, windows_server_2025

Risk scores

CVSS 3.1

Type: Primary
Base score: 9.8
Impact score: 5.9
Exploitability score: 3.9
Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity: CRITICAL

Weaknesses

secure@microsoft.com: CWE-287
nvd@nist.gov: NVD-CWE-noinfo

Hype score: Not currently trending

Configurations

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References

Sources include official advisories and independent security research.