When browsing the web in Google Chrome, most folks rarely think about what’s happening under the hood. But in early 2022, security researchers uncovered a serious flaw—CVE-2022-0794—in Chrome’s WebShare component. In this post, we’ll break down what a “use-after-free” is, how this WebShare bug worked, and show you sample exploit code—all in plain language.

What is CVE-2022-0794?

CVE-2022-0794 is a “use-after-free” vulnerability in the WebShare API of Google Chrome, affecting browser versions before 99..4844.51. In short, a use-after-free bug happens when a program keeps using a piece of memory after it’s already released. This leads to wild behavior—sometimes crash, sometimes code execution.

With this bug, a remote attacker—meaning: anyone in the world—could trick someone into clicking something on a specially crafted web page. If they did, the attacker could potentially get code running in your browser, because of memory corruption (specifically, *heap*—the part of RAM where programs store data dynamically).

Official advisory (Chromium Security):

Google Chrome Releases - CVE-2022-0794

NIST CVE detail:

https://nvd.nist.gov/vuln/detail/CVE-2022-0794

WebShare API: The Basics

The WebShare API lets a webpage open the operating system's native “Share” dialog (like the little popup you see on your phone to share links or files with apps).

Example use

navigator.share({
  title: "Hello world",
  text: "Check out this sweet website!",
  url: "https://example.com";
});

But, as discovered, under certain manipulated HTML and API calls, there was a window for memory misuse.

How the Exploit Worked

Chrome's WebShare had a logic bug. When the browser’s memory (heap) for a share process was “freed” (released), some functions could still keep a reference (a “pointer”) to that chunk of memory. If the exploit triggered a “use” after the memory was already “freed,” the browser could end up running arbitrary code via corrupted data.

Attacker's page tricks the browser into starting a share dialog.

2. During execution, *via crafted events and timing*, the memory of the share process is freed. But, another bit of code in Chrome tries to use it *after it’s already gone*.
3. If the attacker is clever, they can arrange for malicious memory contents to occupy that spot, opening doors for code execution or information leaks.

Proof of Concept (Example Snippet)

> Warning: This is simplified for *education only*. Never run this (or any untrusted code) outside a test environment.

<!DOCTYPE html>
<html>
  <body>
    <button id="exploit">Exploit WebShare</button>
    <script>
      let arr = [];
      document.getElementById('exploit').onclick = function() {
        // Step 1: Call share() and cancel quickly to confuse memory management.
        navigator.share({
          title: "Broken Share",
          text: "Triggering Use After Free!",
          url: location.href
        }).catch(()=>{});

        // Step 2: Flood heap, making it easier to control reuse.
        for (let i = ; i < 10000; i++) {
          arr.push(new Array(100).join('A'));
        }

        // Real exploit would time this right and do advanced steps here.
        alert("If Chrome is vulnerable, you might crash now!");
      };
    </script>
  </body>
</html>

This code floods the browser's heap memory after a call to navigator.share, attempting to provoke a use-after-free (in real-world attacks, this part is far more crafty and complicated). With precise timing and memory manipulation, attackers could hijack the freed memory.

Leak memory contents (private data).

- Run arbitrary code: With sophisticated exploitation, maybe even install malware without you knowing.

Was It Fixed?

Yes. Google patched the bug in version 99..4844.51. If you update Chrome regularly, you’re safe from this issue. But millions of users on old, unpatched systems remain at risk.

Check your version: Go to chrome://settings/help and make sure you're on at least version 99..4844.51 or newer.

Additional References

- Chromium Issue 1307101 (restricted)
- Google Chrome Blog: 2022 Security Fix
- NVD CVE-2022-0794

TL;DR

CVE-2022-0794 was a critical security hole in Chrome’s WebShare API. Attackers could trick you into triggering “use-after-free” memory corruption and potentially seize control. A quick update kept millions safe—but it shows again why browser security matters so much.


> Want to dig deeper?  
> Read the official Google Chrome security post.


*This post is an original, exclusive breakdown of CVE-2022-0794 for the infosec curious. Practice safe browsing!*

Timeline

Published on: 04/05/2022 01:15:00 UTC
Last modified on: 08/15/2022 11:15:00 UTC