CVE-2025-31486: Vite Information Disclosure Vulnerability

CVE-2025-31486 Overview

CVE-2025-31486 is an Information Exposure vulnerability in Vite, a popular frontend tooling framework for JavaScript. The vulnerability allows attackers to bypass the server.fs.deny restriction and retrieve the contents of arbitrary files to the browser. By appending ?.svg with ?.wasm?init or using the sec-fetch-dest: script header, malicious actors can circumvent file system access controls designed to prevent unauthorized file access.

Critical Impact
Arbitrary file disclosure allows attackers to read sensitive configuration files, environment variables, source code, and credentials from Vite development servers exposed to the network.

Affected Products

Vite versions prior to 4.5.12
Vite versions 5.x prior to 5.4.17
Vite versions 6.0.x prior to 6.0.14, 6.1.x prior to 6.1.4, and 6.2.x prior to 6.2.5

Discovery Timeline

2025-04-03 - CVE CVE-2025-31486 published to NVD
2025-04-07 - Last updated in NVD database

Technical Details for CVE-2025-31486

Vulnerability Analysis

This vulnerability exists in the asset handling logic within Vite's development server. The server.fs.deny configuration option is designed to restrict access to sensitive files, but the implementation failed to properly sanitize file paths when processing SVG and WebAssembly file requests. The flaw specifically manifests when processing inline assets, where the bypass is only possible if the requested file is smaller than the build.assetsInlineLimit threshold (default: 4kB) and when using Vite version 6.0 or later.

The vulnerability is classified as CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor). Only applications that explicitly expose the Vite development server to the network using the --host flag or server.host configuration option are affected.

Root Cause

The root cause lies in improper URL cleaning during SVG file processing. The original code passed the raw id parameter (which could contain query string manipulation) to the svgExtRE.test() function before cleaning the URL. This allowed attackers to craft requests that appeared to be for SVG files while actually targeting restricted paths. The vulnerability also extended to WebAssembly module initialization requests through similar path manipulation.

Attack Vector

An attacker can exploit this vulnerability by sending specially crafted HTTP requests to an exposed Vite development server. The attack requires network access to the server and involves appending specific query strings or headers to bypass file system restrictions. The attack vector is network-based, requires high complexity due to specific conditions (file size limits, network exposure), and does not require authentication.

typescript

// Security patch in packages/vite/src/node/plugins/asset.ts
// Source: https://github.com/vitejs/vite/commit/62d7e81ee189d65899bb65f3263ddbd85247b647
 
   // If is svg and it's inlined in build, also inline it in dev to match
   // the behaviour in build due to quote handling differences.
-  if (svgExtRE.test(id)) {
-    const file = publicFile || cleanUrl(id)
+  const cleanedId = cleanUrl(id)
+  if (svgExtRE.test(cleanedId)) {
+    const file = publicFile || cleanedId
     const content = await fsp.readFile(file)
     if (shouldInline(environment, file, id, content, undefined, undefined)) {
       return assetToDataURL(environment, file, content)

The fix ensures that the URL is cleaned before the SVG extension check, preventing query string manipulation from bypassing security controls.

Detection Methods for CVE-2025-31486

Indicators of Compromise

HTTP requests containing ?.svg combined with ?.wasm?init query parameters targeting unexpected file paths
Requests with sec-fetch-dest: script headers attempting to access non-script resources
Access logs showing requests for sensitive files like .env, package.json, or configuration files with SVG/WASM query parameters
Unusual file read operations from the Vite process accessing restricted directories

Detection Strategies

Monitor web server access logs for requests containing suspicious query string combinations (?.svg with ?.wasm?init)
Implement network intrusion detection rules to flag requests with path traversal patterns combined with SVG/WASM extensions
Review Vite development server logs for file access attempts outside permitted directories
Deploy web application firewall rules to block requests matching known exploitation patterns

Monitoring Recommendations

Enable verbose logging on Vite development servers exposed to networks
Set up alerts for requests targeting common sensitive files (.env, credentials, configuration files)
Monitor for anomalous request patterns with unusual header combinations like sec-fetch-dest: script for non-script resources
Implement file integrity monitoring on sensitive configuration files in development environments

How to Mitigate CVE-2025-31486

Immediate Actions Required

Upgrade Vite to patched versions: 4.5.12, 5.4.17, 6.0.14, 6.1.4, or 6.2.5 or later
Avoid exposing Vite development servers to untrusted networks by removing --host flag or server.host configuration
Review server.fs.deny configurations and verify sensitive files are properly protected
Audit access logs for any evidence of exploitation attempts prior to patching

Patch Information

The vulnerability has been fixed in Vite versions 4.5.12, 5.4.17, 6.0.14, 6.1.4, and 6.2.5. The security patch modifies the asset handling logic in packages/vite/src/node/plugins/asset.ts and introduces additional validation in packages/vite/src/node/plugins/wasm.ts. The fix ensures URLs are properly cleaned before extension validation, preventing query string manipulation from bypassing file system restrictions.

For detailed patch information, see the GitHub Security Advisory GHSA-xcj6-pq6g-qj4x and the related commit.

Workarounds

Do not expose Vite development servers to untrusted networks; use only on localhost
Implement network-level access controls (firewall rules, VPN) to restrict who can access development servers
Use a reverse proxy with strict URL validation rules to filter malicious requests before they reach Vite
Increase build.assetsInlineLimit above the size of any sensitive files to prevent inline processing (temporary mitigation only)

bash

# Configuration example - Restrict Vite to localhost only
# In vite.config.js or vite.config.ts:
# export default {
#   server: {
#     host: 'localhost',  // Do not use 'true' or '0.0.0.0'
#     fs: {
#       deny: ['.env', '.env.*', '*.pem', 'package.json']
#     }
#   }
# }

# Upgrade Vite to patched version
npm update vite@latest
# or for specific version
npm install vite@6.2.5