UDFS Elevation of Privilege Vulnerability in Windows

Executive Summary

CVE-2026-49790 is an elevation of privilege vulnerability in the Windows Universal Disk Format File System Driver (UDFS). This vulnerability allows an attacker with low privileges to escalate their access level on a affected system.

The vulnerability is classified with a CVSS v3.1 base score of 7.3, indicating a high severity. The vector AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H means it requires local access (AV:L), low attack complexity (AC:L), low privileges (PR:L), and some user interaction (UI:R). Successful exploitation could lead to high impacts on confidentiality, integrity, and availability (C:H/I:H/A:H).

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Detection Guidance

The provided context does not include specific detection methods or commands for identifying the presence of CVE-2026-49790 on a network or system. Detection typically involves checking for vulnerable versions of the Windows Universal Disk Format File System Driver (UDFS) or applying Microsoft-provided tools or updates.

To check for vulnerable systems, you may need to verify the installed Windows version and patch level. Microsoft often provides guidance or tools in their security updates or the Microsoft Update Catalog. Refer to the official Microsoft resources for the most accurate detection methods.

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Impact Analysis

If exploited, this vulnerability could allow an attacker to gain elevated privileges on your Windows system. This means an attacker with limited access could perform actions with higher permissions, such as installing programs, viewing or modifying sensitive data, or creating new accounts with full user rights.

• Unauthorized access to sensitive files or data stored on the system.
• Installation of malware or other malicious software without your knowledge.
• Disruption of system operations or services, leading to potential downtime.
• Compromise of other systems or networks if the affected system is part of a larger infrastructure.

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Compliance Impact

This vulnerability could have significant implications for compliance with standards and regulations that require protection of sensitive data and system integrity.

• GDPR: If the vulnerability leads to unauthorized access or disclosure of personal data, it could result in a violation of GDPR, which mandates strict protection of personal information. Organizations may face fines or legal consequences if they fail to mitigate such risks.
• HIPAA: For organizations handling protected health information (PHI), exploitation of this vulnerability could lead to unauthorized access to PHI, violating HIPAA's security and privacy rules. This could result in penalties and reputational damage.
• Other standards: Compliance frameworks like ISO 27001, NIST, or PCI DSS require maintaining system security and preventing unauthorized access. Failure to address this vulnerability could lead to non-compliance and potential audit failures.

Organizations should apply the necessary patches or mitigations to avoid potential compliance violations and ensure the security of their systems.

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Mitigation Strategies

To mitigate CVE-2026-49790, apply the security update provided by Microsoft as soon as possible. The update will address the elevation of privilege vulnerability in the Windows Universal Disk Format File System Driver (UDFS).

• Visit the Microsoft Security Response Center (MSRC) update guide for CVE-2026-49790 to download and install the latest patch.
• Ensure all systems running the affected Windows versions are updated to the latest secure version.
• Monitor Microsoft’s official communications for any additional mitigation steps or workarounds if the patch cannot be applied immediately.

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