GHSA-p9ff-h696-f583 CVE-2026-39363

Vite Vulnerable to Arbitrary File Read via Vite Dev Server WebSocket

High npm

Severity: 8.2 / 10; High · CVSS 4.0
Exploit chance (EPSS): 3.40%; Chance of exploitation in the next 30 days. Higher than 88.83% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-200 Exposure of Sensitive Information to an Unauthorized Actor; CWE-306 Missing Authentication for Critical Function
Fix: 8.0.5; Upgrade vite to this version or later

Description

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" /> <img width="1382" height="955" alt="image" src="https://github.com/user-attachments/assets/6a230d2e-197a-4c9c-b373-d0129756d5d7" />

Affected versions

npm

Package	Vulnerable	Fixed in
vite	`>= 8.0.0, <= 8.0.4`	No fix yet
vite	`>= 7.0.0, <= 7.3.1`	No fix yet
vite	`>= 6.0.0, <= 6.4.1`	No fix yet
vite	`>= 8.0.0, < 8.0.5`	`8.0.5`
vite	`>= 7.0.0, < 7.3.2`	`7.3.2`
vite	`>= 6.0.0, < 6.4.2`	`6.4.2`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

vite npm → `8.0.5`

npm

npm install vite@8.0.5

yarn

yarn add vite@8.0.5

pnpm

pnpm add vite@8.0.5

Severity breakdown

CVSS 4.0 8.2

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Attack vector: Network
Attack complexity: Low
Attack requirements: Present
Privileges required: None
User interaction: None
Confidentiality (vulnerable system): High
Integrity (vulnerable system): None
Availability (vulnerable system): None
Confidentiality (subsequent systems): None
Integrity (subsequent systems): None
Availability (subsequent systems): None

CVSS 3.1 7.5

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Weakness

CWE-200: Exposure of Sensitive Information to an Unauthorized Actor

The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

How to prevent it

Architecture and Design: Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

CWE-306: Missing Authentication for Critical Function

The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.

How to prevent it

Architecture and Design: Divide the software into anonymous, normal, privileged, and administrative areas. Identify which of these areas require a proven user identity, and use a centralized authentication capability. Identify all potential communication channels, or other means of interaction with the software, to ensure that all channels are appropriately protected, including those channels that are assumed to be accessible only by authorized parties. Developers sometimes perform authentication at the primary channel, but open up a secondary channel that is assumed to be private. For example, a login mechanism may be listening on one network port, but after successful authentication, it may open up a second port where it waits for the connection, but avoids authentication because it assumes that only the authenticated party will connect to the port. In general, if the software or protocol allows a single session or user state to persist across multiple connections or channels, authentication and appropriate credential management need to be used throughout.
Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Architecture and Design: Where possible, avoid implementing custom, "grow-your-own" authentication routines and consider using authentication capabilities as provided by the surrounding framework, operating system, or environment. These capabilities may avoid common weaknesses that are unique to authentication; support automatic auditing and tracking; and make it easier to provide a clear separation between authentication tasks and authorization tasks. In environments such as the World Wide Web, the line between authentication and authorization is sometimes blurred. If custom authentication routines are required instead of those provided by the server, then these routines must be applied to every single page, since these pages could be requested directly.
Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using libraries with authentication capabilities such as OpenSSL or the ESAPI Authenticator [REF-45].
Implementation, System Configuration, Operation: When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to require strong authentication for users who should be allowed to access the data [REF-1297] [REF-1298] [REF-1302].

References

Advisories

Fixes and patches

Packages

github.com/vitejs/vite

Timeline

Apr 6, 2026 Published
Sep 10, 2026 Last updated by the source
Nov 1, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-4r4m-qw57-chr8 Vite has a `server.fs.deny` bypassed for `inline` and `raw` with `?import` query	High Known exploited	Also affects vite
GHSA-8g5g-mxqh-grgj Vite: `server.fs.deny` bypassed with queries	Medium	Also affects vite
GHSA-vfpm-58rq-9qcg Vite: First 4 bytes of files outside of `server.fs` setting is exposed by `?vite-wasm-instance`	Medium	Also affects vite
GHSA-rq7h-c2jc-7f22 Vite: Files outside `server.fs.allow` could be served when project paths match system paths on non-Windows machine	Medium	Also affects vite
GHSA-9jrq-w75r-8gcw Vite: Cross origin script execution through Vite custom middleware	Low	Also affects vite
GHSA-r825-w8mm-5pxw launch-editor: Editor CLI flag misinterpretation causing arbitrary command execution for some editors	Medium	Also affects vite
GHSA-698v-4r3x-3vcv launch-editor: escapeCmdArgs() omits % escaping on Windows	Medium	Also affects vite
GHSA-587h-7wmj-h5pm launch-editor: `fs.existsSync()` existence check can be bypassed on Windows	High	Also affects vite

Credits: CodeAnt-AI-Security, bluwy, odgrso, tronglinh23

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