CVE-2025-59258 is a vulnerability identified in Microsoft Windows Server 2019, specifically within the Active Directory Federation Services (AD FS) component. The issue is classified under CWE-532, which involves the insertion of sensitive information into log files. In this case, AD FS improperly logs sensitive data, which can be accessed by an unauthorized attacker with local access to the system. The vulnerability does not require any privileges or user interaction, making it easier to exploit for someone with local access. The sensitive information exposure could include authentication tokens, credentials, or other identity federation details that are critical for security. Although the vulnerability does not impact system integrity or availability, the confidentiality breach could facilitate further attacks or unauthorized access if the leaked information is leveraged. The CVSS v3.1 score is 6.2 (medium), reflecting the local attack vector and the lack of required privileges but high confidentiality impact. No known exploits have been reported in the wild, and no patches have been published at the time of disclosure. Organizations relying on AD FS for identity federation should be aware of this issue and monitor for updates from Microsoft. The vulnerability highlights the risk of sensitive data exposure through logging mechanisms, a common but often overlooked security concern.

For European organizations, the primary impact of CVE-2025-59258 is the potential unauthorized disclosure of sensitive identity federation information stored in AD FS logs. This could lead to credential compromise, unauthorized access to federated services, and lateral movement within enterprise networks. Organizations in sectors with stringent data protection requirements, such as finance, healthcare, and government, face increased risk due to the sensitivity of the leaked information. The vulnerability requires local access, so the threat is higher in environments where multiple users have physical or remote local access to servers, such as shared data centers or managed service providers. The confidentiality breach could undermine trust in identity federation setups and complicate compliance with GDPR and other privacy regulations. Although no direct availability or integrity impact exists, the indirect consequences of leaked credentials or tokens could be severe, including privilege escalation and data breaches. European enterprises using Windows Server 2019 AD FS must consider this vulnerability in their risk assessments and incident response planning.

To mitigate CVE-2025-59258, organizations should immediately restrict and audit local access to Windows Server 2019 systems running AD FS, ensuring only trusted administrators have access to log files. Implement strict file system permissions on log directories to prevent unauthorized reading of sensitive logs. Enable enhanced monitoring and alerting for unusual access patterns to AD FS logs. Review and sanitize logging configurations to minimize sensitive data capture until a patch is available. Employ network segmentation and host-based controls to limit lateral movement from compromised local accounts. Prepare for rapid deployment of Microsoft patches once released by subscribing to official security advisories. Additionally, consider deploying endpoint detection and response (EDR) solutions to detect suspicious local access activities. Conduct regular security training for administrators on the risks of sensitive data exposure through logs. Finally, evaluate alternative identity federation solutions or configurations that reduce sensitive data logging if feasible.