CVE-2024-23331 in Vite
Summary
by MITRE • 01/19/2024
Vite is a frontend tooling framework for javascript. The Vite dev server option `server.fs.deny` can be bypassed on case-insensitive file systems using case-augmented versions of filenames. Notably this affects servers hosted on Windows. This bypass is similar to CVE-2023-34092 -- with surface area reduced to hosts having case-insensitive filesystems. Since `picomatch` defaults to case-sensitive glob matching, but the file server doesn't discriminate; a blacklist bypass is possible. By requesting raw filesystem paths using augmented casing, the matcher derived from `config.server.fs.deny` fails to block access to sensitive files. This issue has been addressed in [email protected], [email protected], [email protected], and [email protected]. Users are advised to upgrade. Users unable to upgrade should restrict access to dev servers.
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Analysis
by VulDB Data Team • 01/19/2024
The vulnerability CVE-2024-23331 affects the Vite frontend tooling framework, specifically targeting the server filesystem access controls implemented through the `server.fs.deny` configuration option. This flaw represents a critical security weakness that undermines the intended access restrictions on development servers, particularly impacting systems with case-insensitive filesystems such as those running on Windows operating systems. The vulnerability stems from an inconsistent handling of case sensitivity between the picomatch library's default behavior and Vite's server implementation, creating a path traversal bypass opportunity that could expose sensitive files to unauthorized access.
The technical implementation of this vulnerability exploits the fundamental mismatch between case-sensitive and case-insensitive filesystem behaviors. While picomatch, the glob matching library used by Vite, defaults to case-sensitive matching patterns, the development server's file access controls do not enforce case discrimination when evaluating deny rules. This discrepancy allows attackers to craft filenames with altered casing patterns that bypass the intended blacklist filtering mechanism. When a request is made using case-augmented filenames, the server's matcher fails to recognize these variations as matching the denied patterns, effectively allowing access to files that should remain restricted. The vulnerability is particularly concerning because it operates on the principle of filesystem case insensitivity, where Windows systems treat files with different casing as identical, while the application logic treats them as distinct.
This security flaw has significant operational impact on development environments that rely on Vite's built-in server functionality. Attackers can leverage this bypass to access sensitive files including configuration files, source code, documentation, and potentially credentials stored in the project directory. The vulnerability affects all versions of Vite prior to 5.0.12, 4.5.2, 3.2.8, and 2.9.17, representing a substantial portion of the user base that may be exposed to this risk. The issue is classified under CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and aligns with ATT&CK technique T1059.001 (Command and Scripting Interpreter: PowerShell) and T1566 (Phishing) when considering how attackers might exploit the exposed files to gather intelligence or establish persistence. The bypass mechanism is similar to CVE-2023-34092 but with reduced attack surface focused specifically on case-insensitive filesystem environments.
The recommended mitigation strategy involves upgrading to one of the patched Vite versions that address this specific inconsistency between the filesystem access controls and the glob matching behavior. Organizations unable to immediately upgrade should implement additional network-level restrictions to limit access to development servers, particularly when these servers are exposed to untrusted networks or users. Implementing proper firewall rules to restrict access to development server ports and ensuring that development servers are only accessible from trusted network segments provides an additional layer of defense. The vulnerability demonstrates the importance of considering filesystem characteristics during security implementation and highlights how seemingly minor differences in case handling can create substantial security implications in application frameworks that manage filesystem access controls. Security teams should also consider implementing monitoring for unusual file access patterns that might indicate exploitation attempts.