CVE-2025-50166 is a vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0) specifically affecting the Windows Distributed Transaction Coordinator (DTC) component. The vulnerability is classified as an integer overflow or wraparound issue (CWE-190). Integer overflow occurs when an arithmetic operation attempts to create a numeric value that is outside the range that can be represented with a given number of bits, causing the value to wrap around to an unintended value. In this case, the flaw in the DTC component allows an authorized attacker—meaning the attacker must have some level of legitimate access privileges—to exploit this integer overflow to disclose sensitive information over a network. The vulnerability does not require user interaction and can be exploited remotely (AV:N), with low attack complexity (AC:L). The attacker must have privileges (PR:L), but no UI interaction is needed (UI:N). The scope is unchanged (S:U), and the impact is primarily on confidentiality (C:H) with no impact on integrity or availability (I:N, A:N). The CVSS v3.1 base score is 6.5, indicating a medium severity level. No known exploits are currently reported in the wild, and no patches or mitigation links are provided at this time. The vulnerability was reserved in June 2025 and published in August 2025. The Windows Distributed Transaction Coordinator is a critical system service that manages transactions across multiple resource managers, such as databases and message queues, which means that exploitation could potentially expose sensitive transactional data or metadata to an attacker with network access and limited privileges.

For European organizations, this vulnerability poses a risk primarily to confidentiality of sensitive transactional data managed by Windows DTC on affected Windows 10 Version 1809 systems. Many enterprises and governmental agencies in Europe rely on Windows 10 in their IT infrastructure, including legacy systems that have not been upgraded beyond version 1809. The exposure of confidential information could lead to data breaches, loss of intellectual property, or leakage of personally identifiable information (PII), which would have regulatory implications under GDPR. Since the vulnerability requires an authorized user with network access, insider threats or compromised credentials could be leveraged to exploit this flaw. The lack of impact on integrity and availability reduces the risk of system disruption or data manipulation, but confidentiality breaches alone can have severe reputational and compliance consequences. Organizations using distributed transactions in financial, healthcare, or critical infrastructure sectors are particularly at risk due to the sensitivity of the data handled by DTC.

Given the absence of an official patch at the time of this report, European organizations should take immediate steps to mitigate risk. First, they should identify and inventory all systems running Windows 10 Version 1809, especially those utilizing the Distributed Transaction Coordinator service. Restrict network access to DTC ports and services to only trusted and necessary hosts, employing network segmentation and firewall rules to limit exposure. Implement strict access controls and monitor for unusual authorized user activity that could indicate exploitation attempts. Employ enhanced logging and network traffic analysis focused on DTC communications to detect potential information disclosure attempts. Organizations should plan to upgrade affected systems to a supported and patched Windows version as soon as updates become available. Additionally, enforcing multi-factor authentication (MFA) and strong credential management reduces the risk of attackers gaining the required authorized access. Finally, maintain up-to-date backups and incident response plans tailored to data breach scenarios involving confidential information exposure.