CVE-2026-83683 in Windows
Summary
by MITRE • 10/14/2026
Absolute path traversal in Windows Encrypting File System (EFS) allows an authorized attacker to disclose information over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described involves a critical flaw within the Microsoft Windows Encrypting File System, specifically manifesting as an absolute path traversal issue. This security defect permits an authenticated user or process with appropriate privileges on the local system to manipulate file paths in a manner that bypasses intended access controls. By constructing specific requests that include absolute path sequences rather than relative ones, an attacker can direct the EFS subsystem to read files from arbitrary locations on the disk volume. This capability effectively neutralizes the security boundary established by the operating system's directory structure, allowing for unauthorized data exfiltration beyond the scope of the user's intended file access permissions.
From a technical perspective, this flaw stems from insufficient validation or sanitization of path inputs within the EFS API handlers. When applications interact with encrypted files, they typically rely on the underlying kernel-mode components to resolve paths and verify encryption keys before granting read access. In this scenario, the system fails to properly restrict absolute path references, leading to a situation where sensitive data stored in protected directories can be accessed by processes that should not have visibility into those locations. The exploitation of this vulnerability does not require privilege escalation beyond what is already granted to the attacker; rather, it abuses existing permissions through improper input handling within the file system encryption layer.
The operational impact of this vulnerability centers on confidentiality and data integrity. An authorized attacker can leverage this flaw to disclose sensitive information over a network if the accessed files are subsequently transmitted or shared externally. This could include personal identifiable information, corporate secrets, financial records, or other classified data stored in encrypted folders that were presumed secure due to EFS protections. The ability to read arbitrary files undermines the fundamental promise of encryption at rest for those specific directories, creating significant risks for organizations relying on Windows native file encryption as a primary security control.
This vulnerability aligns with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, which categorizes flaws where software does not properly validate input paths against expected directory boundaries. Additionally, it relates to ATT&CK technique T1083: File and Directory Discovery, as the attacker uses this mechanism to enumerate and access restricted files on the system. Mitigation strategies primarily involve applying vendor-supplied security patches that address the path validation logic within the EFS subsystems. Organizations should also enforce strict least-privilege principles for user accounts interacting with sensitive file systems and consider implementing additional monitoring solutions to detect unusual patterns of file access or path manipulation attempts across network shares.