SMB Server Vulnerability Impacts Microsoft Products
CVE-2025-55234

8.8HIGH

Key Information:

Vendor: Microsoft
Status: Windows 10 Version 1809; Windows Server 2019; Windows Server 2019 (server Core Installation); Windows Server 2022
Vendor: CVE Published:; 9 September 2025

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What is CVE-2025-55234?

CVE-2025-55234 is a security vulnerability identified in Microsoft’s Server Message Block (SMB) Server, a network file sharing protocol widely used for resource sharing across computers in a network. This vulnerability may allow attackers to conduct relay attacks depending on how the SMB Server is configured, leading to elevation of privilege attacks on users. An attacker exploiting this vulnerability can manipulate authenticated sessions to gain unauthorized access to resources and potentially execute malicious actions within the environment. This poses a considerable risk to organizations, as it undermines the integrity and confidentiality of their networks and sensitive data.

To mitigate this vulnerability, Microsoft has implemented features such as SMB Server signing and Extended Protection for Authentication (EPA). These are designed to bolster security against relay attacks, but their effectiveness is contingent upon proper configuration and prior implementation. Microsoft is advising customers to assess their systems using newly provided auditing capabilities to identify any vulnerabilities before deploying further protective measures.

Potential impact of CVE-2025-55234

Elevation of Privilege Attacks: Successful exploitation of this vulnerability could permit attackers to elevate their access privileges within the network, allowing them to perform unauthorized actions and access sensitive information or resources.
Increased Risk of Data Breaches: Given the potential for unauthorized access, this vulnerability heightens the likelihood of data breaches, where sensitive organizational data could be exfiltrated or manipulated by malicious actors.
Network Integrity Compromise: The ability for attackers to perform relay attacks can destabilize network integrity, leading to a cascade of security issues, increased vulnerability to subsequent attacks, and overall diminished trust in the security framework of the organization.