CVE-2019-14322 in Werkzeug
Summary
by MITRE
In Pallets Werkzeug before 0.15.5, SharedDataMiddleware mishandles drive names (such as C:) in Windows pathnames.
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Analysis
by VulDB Data Team • 09/27/2025
The vulnerability identified as CVE-2019-14322 affects the Pallets Werkzeug web framework version 0.15.4 and earlier, specifically within the SharedDataMiddleware component. This middleware is designed to serve static files from various directories and is commonly used in web applications built on the Werkzeug framework. The issue arises from improper handling of Windows drive names in file path operations, creating a potential security risk that could be exploited by attackers to manipulate file access patterns and potentially gain unauthorized access to system resources.
The technical flaw manifests when the SharedDataMiddleware processes Windows-style file paths that contain drive specifications such as C:, D:, or other drive letters. The middleware fails to properly sanitize or validate these path components, leading to potential path traversal vulnerabilities. When a request is made to access static files, the middleware incorrectly interprets the drive letter as part of the path structure rather than as a separate drive identifier. This misinterpretation can cause the application to resolve file paths in unexpected ways, potentially allowing attackers to access files outside the intended directory structure.
The operational impact of this vulnerability extends beyond simple path manipulation issues and can be leveraged for more serious security breaches. An attacker could potentially exploit this flaw to access system files, configuration data, or other sensitive resources that should normally be protected from direct web access. The vulnerability is particularly concerning in environments where the Werkzeug framework is used to serve static content and where the application might be running with elevated privileges. The improper handling of Windows drive names creates a window of opportunity for path traversal attacks that could lead to unauthorized data access or even system compromise.
This vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal. The issue also relates to ATT&CK technique T1083, which involves discovering file and directory permissions, as the flawed path handling could expose file system structures that should remain hidden. The security implications are compounded by the fact that this affects a core middleware component that is widely used in Python web applications, making the potential attack surface quite broad. Organizations using Werkzeug versions prior to 0.15.5 should prioritize patching this vulnerability to prevent potential exploitation.
The recommended mitigation strategy involves upgrading to Werkzeug version 0.15.5 or later, which includes proper handling of Windows drive names in path operations. Additionally, administrators should implement proper input validation and sanitization for all file path operations, particularly in environments where Windows-style paths are processed. Network segmentation and access controls should be reviewed to limit the potential impact of any successful exploitation attempts. Security monitoring should be enhanced to detect unusual file access patterns that might indicate path traversal attempts. Regular security assessments of web applications using Werkzeug should include verification of middleware components to ensure they are properly configured and patched against known vulnerabilities.