In July 2023, Google patched a critical vulnerability identified as CVE-2023-4072. It affected WebGL in Chrome before version 115..579.170. This bug allowed a remote attacker to trigger heap corruption in Chrome—just by crafting a malicious HTML page. If you ever wondered why Chrome updates matter, this is a prime example. Let’s dive into what this means, how the issue arises, and how an attacker could exploit it.

What is WebGL and Why Was It Affected?

WebGL is a browser feature that lets web developers create fast, interactive 3D graphics in your browser. It is tightly linked to your computer’s hardware and memory (via the GPU). If there’s a security hole here, just viewing a webpage could put your system at risk.

CVE-2023-4072 was about out-of-bounds read and write in the WebGL component of Chrome. In other words, Chrome could be tricked into accessing memory it shouldn’t—either reading (leaking data) or writing (corrupting memory).

The Vulnerability: How Does it Work?

Malicious HTML and JavaScript can send unexpected data to WebGL. Chrome failed to verify that this data stayed within “safe” bounds. With special code, a hacker could:

Read sensitive information from your memory (like session tokens)

- Write or overwrite other parts of the browser's memory (leading to crashes or, worse, code execution)

In security lingo, this is a heap corruption bug.

Here’s a simplified code snippet to show how an attacker might trigger the bug

<!-- A crafted HTML page targeting WebGL out-of-bounds -->
<canvas id="myCanvas" width="100" height="100"></canvas>
<script>
  const canvas = document.getElementById('myCanvas');
  const gl = canvas.getContext('webgl');

  // Create a buffer with controlled data
  const buffer = gl.createBuffer();
  gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
  
  // Float32Array size larger than specified
  let largeArray = new Float32Array(100);
  for(let i = ; i < largeArray.length; ++i)
    largeArray[i] = Math.random();

  // Crafted call: overflow possible in affected Chrome versions
  gl.bufferData(gl.ARRAY_BUFFER, largeArray, gl.STATIC_DRAW);

  // Use faulty index / size—trigger the out-of-bounds bug.
  gl.vertexAttribPointer(, 1024, gl.FLOAT, false, , );
  gl.enableVertexAttribArray();

  // Will cause out-of-bounds operations internally
  gl.drawArrays(gl.TRIANGLES, , 3);
</script>

Note: Modern, updated Chrome versions are immune to this snippet due to security checks added after CVE-2023-4072.

Severity: High

- Remote code execution is possible: If the attacker can control both reads and writes to heap memory, they can sometimes hijack browser execution. This means malware, spyware, or ransomware—without download prompts.

Exploitation in the Wild

At the time of writing, there is no public “weaponized” exploit released, but similar bugs in WebGL have been showcased at security conferences and in bug bounties. With detailed bug reports and a crafted exploit (sometimes only 20–50 lines of JavaScript), attackers can reach arbitrary memory zones, crashing the browser or leaking secrets.

Chrome 115..579.170 and later

If you’re running an older version, update ASAP!

References

- Chromium Bug Tracker: Issue 1460695 *(May require login to view full details)*
- Chrome Release Notes (Stable Channel Update for Desktop – 2023-07-20)
- NVD entry for CVE-2023-4072

Enable automatic updates: Let Chrome install security fixes right away.

3. Stay cautious: Only load trusted web pages and browser-based games/graphics.

Conclusion

CVE-2023-4072 is a textbook case of how a seemingly small memory error in a browser feature can have huge consequences. It’s a reminder that browsers are complex, powerful—and targeted daily by hackers. Keeping your browser up-to-date is your best defense against these evolving threats.

Stay safe, and keep your Chrome updated!

*Made for security-minded readers who want the whole story—simply told. Share, but patch first!*

Timeline

Published on: 08/03/2023 01:15:00 UTC
Last modified on: 08/12/2023 06:20:00 UTC