CVE-2026-39364: Vite Information Disclosure Vulnerability

CVE-2026-39364 Overview

CVE-2026-39364 is a security bypass vulnerability affecting Vite, a popular frontend tooling framework for JavaScript. This vulnerability allows attackers to retrieve sensitive files that should be blocked by the server.fs.deny configuration on the Vite development server. Files such as .env environment configuration files and certificate files (*.crt) can be accessed by appending specific query parameters to HTTP requests, resulting in HTTP 200 responses instead of being properly denied.

Critical Impact

Attackers can bypass file access restrictions to read sensitive configuration files including environment variables containing secrets, credentials, and certificates, potentially leading to full application compromise.

Affected Products

• Vite versions 7.1.0 to before 7.3.2
• Vite versions 8.0.0 to before 8.0.5

Discovery Timeline

• 2026-04-07 - CVE CVE-2026-39364 published to NVD
• 2026-04-08 - Last updated in NVD database

Technical Details for CVE-2026-39364

Vulnerability Analysis

This vulnerability represents an Improper Input Validation issue (CWE-180) in the Vite development server's file access control mechanism. The server.fs.deny configuration is designed to prevent access to sensitive files during development, but the implementation fails to properly validate file paths when certain query parameters are present.

When a request includes query parameters such as ?raw, ?import&raw, or ?import&url&inline, the file access validation logic is bypassed. This allows attackers to retrieve the contents of files that would normally be blocked, including environment files containing API keys, database credentials, and other sensitive configuration data.

The vulnerability is particularly concerning because .env files commonly store production secrets during development, and certificate files could enable man-in-the-middle attacks or impersonation of trusted services.

Root Cause

The root cause stems from improper handling of query parameters in the file path resolution logic. The server.fs.deny check appears to be performed before or without consideration of special query parameter handling, creating an inconsistency between the access control decision and the actual file serving behavior. When these specific query parameters are appended, the request processing follows a different code path that does not honor the deny list configuration.

Attack Vector

The attack is network-accessible and requires no authentication or user interaction. An attacker with network access to a Vite development server can craft HTTP GET requests with the vulnerable query parameters appended to file paths that would normally be denied.

For example, requesting /path/to/.env?raw or /path/to/.env?import&raw would return the contents of the .env file with an HTTP 200 response, even when .env is properly configured in server.fs.deny. The attack complexity is low as it only requires appending query strings to standard file requests.

Detection Methods for CVE-2026-39364

Indicators of Compromise

• Unusual HTTP requests to the Vite development server containing ?raw, ?import&raw, or ?import&url&inline query parameters targeting sensitive files
• Access logs showing requests for .env, *.crt, *.key, or other files that should be blocked by server.fs.deny
• HTTP 200 responses for files that are configured in the deny list

Detection Strategies

• Monitor web server access logs for requests containing suspicious query parameter combinations targeting sensitive file extensions
• Implement Web Application Firewall (WAF) rules to detect and alert on requests attempting to access known sensitive file patterns with raw/import query parameters
• Configure intrusion detection systems to identify patterns consistent with file disclosure attempts

Monitoring Recommendations

• Enable detailed access logging on all Vite development server instances
• Set up alerts for any requests targeting .env, certificate files, or other sensitive file types
• Review network traffic for reconnaissance patterns that may indicate automated scanning for this vulnerability

How to Mitigate CVE-2026-39364

Immediate Actions Required

• Upgrade Vite to version 7.3.2 or later for the 7.x branch
• Upgrade Vite to version 8.0.5 or later for the 8.x branch
• Restrict network access to development servers to trusted networks only
• Review access logs for any evidence of exploitation attempts

Patch Information

The Vite development team has released security patches addressing this vulnerability. Version 7.3.2 fixes the issue for users on the 7.x release branch, while version 8.0.5 provides the fix for users on the 8.x branch. For complete technical details and patch information, refer to the GitHub Security Advisory GHSA-v2wj-q39q-566r.

Workarounds

• Ensure Vite development servers are never exposed to untrusted networks or the public internet
• Use network segmentation and firewall rules to restrict access to development environments
• Consider implementing a reverse proxy in front of the Vite server that strips or blocks requests with the vulnerable query parameters
• Move sensitive files outside of the project directory structure where possible