N/A

CVSS Score

-

CVSS Score

Basic Information

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GHSA-p9ff-h696-f583

GHSA-p9ff-h696-f583: Vite Vulnerable to Arbitrary File Read via Vite Dev Server WebSocket

Summary

server.fs check was not enforced to the fetchModule method that is exposed in Vite dev server's WebSocket.

Impact

Only apps that match the following conditions are affected:

explicitly exposes the Vite dev server to the network (using --host or server.host config option)
WebSocket is not disabled by server.ws: false

Arbitrary files on the server (development machine, CI environment, container, etc.) can be exposed.

Details

If it is possible to connect to the Vite dev server’s WebSocket without an Origin header, an attacker can invoke fetchModule via the custom WebSocket event vite:invoke and combine file://... with ?raw (or ?inline) to retrieve the contents of arbitrary files on the server as a JavaScript string (e.g., export default "...").

The access control enforced in the HTTP request path (such as server.fs.allow) is not applied to this WebSocket-based execution path.

PoC

Start the dev server on the target Example (used during validation with this repository):
```
pnpm -C playground/alias exec vite --host 0.0.0.0 --port 5173
```
Confirm that access is blocked via the HTTP path (example: arbitrary file)
```
curl -i 'http://localhost:5173/@fs/etc/passwd?raw'
```
Result: 403 Restricted (outside the allow list) <img width="3898" height="1014" alt="image" src="https://github.com/user-attachments/assets/f6593377-549c-45d7-b562-5c19833438af" />
Confirm that the same file can be retrieved via the WebSocket path By connecting to the HMR WebSocket without an Origin header and sending a vite:invoke request that calls fetchModule with a file://... URL and ?raw, the file contents are returned as a JavaScript module.
<img width="1049" height="296" alt="image" src="https://github.com/user-attachments/assets/af969f7b-d34e-4af4-8adb-5e2b83b31972" />

(GitHub Advisory)

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GHSA-p9ff-h696-f583

GHSA-p9ff-h696-f583:

N/A

CVSS Score

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
vite	npm	>= 8.0.0, <= 8.0.4	8.0.5
vite	npm	>= 7.0.0, <= 7.3.1	7.3.2
vite	npm	>= 6.0.0, <= 6.4.1	6.4.2

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability allows an attacker to read arbitrary files on a developer's machine if the Vite dev server is exposed to the network. This is due to a missing security check in the WebSocket handling logic.

The attack path begins when an attacker connects to the Vite dev server's WebSocket, bypassing standard browser Origin-based security by omitting the header. From there, they can send a specially crafted message to invoke the DevEnvironment.fetchModule method. This method is intended for Hot Module Replacement (HMR) but was insecurely exposed.

The fetchModule method, in turn, calls the internal loadAndTransform function to retrieve the requested module's content. The core of the vulnerability lies here: the loadAndTransform function did not enforce the server.fs.allow filesystem access control policy when called from the WebSocket path. This allowed an attacker to request any file on the system using a file:// URL, and Vite would read and return its contents.

The patch addresses this in two ways: first, it disables the fetchModule method for all default client-side environments, effectively closing the primary attack vector. Second, it refactors the loadAndTransform function to always perform the filesystem access check unless explicitly told not to via a new skipFsCheck flag, which is only intended for trusted server-to-server communication.

Vulnerable functions

DevEnvironment.fetchModule

packages/vite/src/node/server/environment.ts

This function is the entry point for the vulnerability. It is exposed over the Vite development server's WebSocket and could be invoked by an unauthenticated attacker. The function would then process the request to fetch a module, which led to an arbitrary file read because the necessary security checks were not performed in the downstream functions for this execution path. The patch adds a check to disable this function by default in client-facing environments.

loadAndTransform

packages/vite/src/node/server/transformRequest.ts

This function contains the core logic flaw. It is responsible for loading file content from the disk. Before the patch, it lacked enforcement of the `server.fs.allow` access control list when invoked via the WebSocket `fetchModule` path. It previously used an optional `allowId` callback which was not supplied in the vulnerable path. The patch fixes this by adding a mandatory filesystem access check (`isServerAccessDeniedForTransform`) that is only bypassed if an explicit `skipFsCheck` flag is provided for trusted, non-networked server transports.

transformRequest

packages/vite/src/node/server/transformRequest.ts

This function serves as an intermediary to `loadAndTransform`. Its signature was changed to require an `options` object containing the `skipFsCheck` flag. This change ensures that any call to this function must explicitly decide whether to apply the filesystem security check, removing the ambiguity that led to the vulnerability. The vulnerable call path from the WebSocket did not provide the necessary options to enforce the check.

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WAF Rule

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Reasoning

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