CVE-2024-23340 in node-server
Summary
by MITRE • 01/23/2024
@hono/node-server is an adapter that allows users to run Hono applications on Node.js. Since v1.3.0, @hono/node-server has used its own Request object with `url` behavior that is unexpected. In the standard API, if the URL contains `..`, here called "double dots", the URL string returned by Request will be in the resolved path. However, the `url` in @hono/node-server's Request as does not resolve double dots, so `http://localhost/static/.. /foo.txt` is returned. This causes vulnerabilities when using `serveStatic`. Modern web browsers and a latest `curl` command resolve double dots on the client side, so this issue doesn't affect those using either of those tools. However, problems may occur if accessed by a client that does not resolve them. Version 1.4.1 includes the change to fix this issue. As a workaround, don't use `serveStatic`.
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Analysis
by VulDB Data Team • 01/23/2024
The vulnerability described in CVE-2024-23340 affects the hono/node-server package, which serves as an adapter for running Hono applications on Node.js platforms. This issue emerged in version 1.3.0 and persists through the affected release, creating a path traversal vulnerability through improper URL handling within the custom Request object implementation. The flaw specifically manifests when processing URLs containing double dots or "parent directory" references, which are commonly used in path traversal attacks to access files outside the intended directory structure. The vulnerability stems from the package's deviation from standard web server behavior where URL resolution typically normalizes parent directory references, but hono/node-server's implementation fails to perform this normalization.
The technical implementation of this vulnerability lies in how the custom Request object handles URL parsing and resolution. In standard web server implementations, when a URL contains double dots such as in http://localhost/static/.. /foo.txt, the server's URL resolver would normalize this to a canonical path, effectively resolving the parent directory reference and preventing access to unintended file locations. However, @hono/node-server's Request object maintains the raw URL string without normalization, allowing the double dot sequences to persist in the resolved URL. This behavior creates a security gap when combined with the serveStatic middleware functionality, as the application may inadvertently serve files from directories outside the intended static content root. This represents a deviation from the expected behavior defined in web server standards and creates a potential for unauthorized file access.
The operational impact of this vulnerability extends beyond simple path traversal concerns to encompass broader security implications for web applications using this package. While modern web browsers and recent curl implementations automatically resolve double dot sequences on the client side, the vulnerability remains exploitable when accessed through clients that do not perform this resolution, such as older browser versions, custom HTTP clients, or specific network tools. This creates a scenario where attackers could potentially access sensitive files or directories that should be protected from direct web access. The vulnerability is particularly concerning because it affects applications that rely on serveStatic middleware for serving static content, making it a potential vector for information disclosure attacks. The issue demonstrates how seemingly minor implementation differences in web server components can create significant security risks, especially in environments where client-side URL normalization is not guaranteed.
The mitigation strategy for this vulnerability involves upgrading to version 1.4.1 or later, which includes the necessary changes to properly normalize URL paths containing double dots. This fix aligns the package's behavior with standard web server expectations and resolves the path traversal vulnerability at its source. As a temporary workaround, developers can avoid using the serveStatic middleware entirely, though this approach limits functionality and may not be practical for all applications. The vulnerability highlights the importance of adhering to established web server standards and proper URL handling practices, as defined in common security frameworks and best practices. From an ATT&CK perspective, this vulnerability maps to techniques involving path traversal and information disclosure, while the CWE classification would fall under CWE-22 Path Traversal, specifically demonstrating how improper input validation and URL normalization can create security weaknesses in web applications. Organizations should ensure their dependency management systems are updated to prevent deployment of vulnerable versions, and security teams should monitor for applications using this package that may be exposed to similar path traversal risks.