CVE-2026-102217 in Windows
Summary
by MITRE • 10/13/2026
Improper resolution of path equivalence in WebDAV allows an authorized attacker to elevate privileges over a network.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability described involves an improper resolution of path equivalence within the Web Distributed Authoring and Versioning (WebDAV) protocol implementation, which serves as a critical attack vector for privilege escalation by authenticated users. This flaw typically stems from how the server processes URL paths containing special characters, symbolic links, or redundant directory traversals such as double slashes or encoded sequences like percent-encoding of forward slashes. In many enterprise environments, WebDAV is enabled to facilitate remote file management and collaboration, but when the underlying path resolution logic fails to normalize these inputs correctly before applying access control checks, it creates a discrepancy between the intended resource location and the actual filesystem target. An attacker who has already obtained valid credentials can exploit this inconsistency by crafting specific HTTP requests that manipulate the request URI to reference files or directories outside of their authorized scope, effectively bypassing directory-based restrictions designed to isolate user data.
From a technical perspective, the core issue lies in the order of operations during request handling. Ideally, path normalization should occur before any authorization decisions are made, ensuring that all subsequent checks apply to the canonical absolute path on the disk. However, if the system performs access control verification against the raw or partially normalized URI while subsequently resolving the actual file path using a different algorithm, an attacker can inject sequences that resolve to sensitive system files, configuration directories, or other users' private data upon execution. This mechanism allows for unauthorized read operations, which may lead to information disclosure of confidential documents, source code, or credentials stored in plaintext configurations. Furthermore, if write permissions are granted based on the flawed path check but applied to a different physical location due to the equivalence resolution error, an attacker could overwrite critical system files, modify application logic, or inject malicious scripts into web-accessible directories, thereby achieving remote code execution with elevated privileges.
The operational impact of this vulnerability is severe because it transforms a standard authenticated user account into a powerful tool for lateral movement and persistence within the network infrastructure. Once an attacker gains access to sensitive data through information disclosure, they can harvest credentials or internal network maps that facilitate further attacks against more critical systems. If write capabilities are exploited, the consequences extend beyond data theft to include service disruption via file deletion or corruption, as well as complete system compromise if configuration files such as web server settings or application initialization scripts are modified. This type of flaw is particularly dangerous in cloud-hosted environments and enterprise intranets where WebDAV services often have broad network exposure, making them attractive targets for automated scanning tools that specifically probe for path traversal weaknesses in HTTP-based file transfer protocols.
To mitigate this risk, organizations must ensure that their web server software and application frameworks are updated to the latest versions provided by vendors, as these updates typically include patches that enforce strict canonicalization of all incoming request paths before authorization checks occur. Administrators should review WebDAV configurations to disable unnecessary methods such as PUT, DELETE, or MKCOL if they are not strictly required for business operations, thereby reducing the attack surface available to authenticated users. Additionally implementing a web application firewall with rules specifically designed to detect and block anomalous path sequences can provide an additional layer of defense by intercepting requests that contain encoded slashes or excessive dot-dot segments before they reach the backend processing logic. Regular security audits focusing on input validation and access control enforcement for file-serving endpoints are essential to identify similar implementation flaws across other services within the infrastructure, ensuring that privilege boundaries remain intact even when attackers possess valid authentication tokens. This vulnerability aligns with CWE-22 Improper Limitation of a Pathname to a Restricted Directory and is often associated with ATT&CK technique T1083 File and Directory Discovery, highlighting its role in reconnaissance and unauthorized access phases of an attack lifecycle.