Security flaws in browsers often pose significant risks. One such issue, tracked as CVE-2023-3217, is a use-after-free vulnerability in the WebXR feature of Google Chrome. Before version 114..5735.133, a skilled remote attacker could exploit this bug using a custom HTML page, potentially leading to heap corruption and browser compromise. The Chromium team rated this as a High severity issue, and understanding it helps users and developers stay safer online.

What is WebXR?

WebXR is a set of APIs in modern browsers that allow web applications to access virtual and augmented reality devices. It brings VR and AR into browsers, but new tech can introduce new weaknesses.

Understanding Use-After-Free

A use-after-free happens when a program continues to use a chunk of memory after it has been released (freed). This can corrupt memory. Attackers may exploit these conditions to run malicious code, crash applications, or escape sandboxes.

Affected Versions: Chrome before 114..5735.133

- Type: Use-After-Free in the way WebXR handled some memory during interaction with custom HTML pages
- Possible Result: Heap corruption, browser crashes, or arbitrary code execution in the context of the browser

Official Coverage

- Chromium blog post
- NVD entry
- Chromium Issue 1446448 (crbug.com)

How Attackers Exploited It

To exploit this vulnerability, an attacker would lure a victim to a specially crafted web page. The page would use JavaScript to manipulate WebXR in a way that causes a related object (like a session or resource) to get freed (deleted) but still be used.

Below is a simplified pseudocode to demonstrate the possible exploitation flow (this is not working exploit code, but helps to understand):

// Warning: Example for educational purposes only!
let xrSession;

navigator.xr.requestSession("immersive-vr").then(session => {
    xrSession = session;

    // Trigger some event that causes the session to be freed
    xrSession.addEventListener("end", () => {
        // The session object is no longer valid here
        // Accessing it could lead to use-after-free
        xrSession.updateRenderState({ baseLayer: null });
    });

    // Induce the 'end' event
    xrSession.end();
});

The attacker crafts JavaScript to cause a WebXR session object (xrSession) to be freed (ended), but tries to access it immediately after. If Chrome mishandles these objects, memory corruption can happen. Attackers can use such a primitive with other browser weaknesses to control program execution.

The real-world exploitation often involves heap-spraying and precise timing, sometimes with the help of additional bugs (or "primitives"). The above code is a greatly simplified example to clarify the pattern.

Mitigation

- Update Chrome. If you haven’t updated past version 114..5735.133, you’re vulnerable. Chrome auto-updates, but check your About page to confirm.
- Watch for patches. Google’s security blog and the Chromium Releases are the best places to learn about new vulnerabilities.

A use-after-free vulnerability in WebXR is powerful because

- VR/AR APIs are increasingly popular, and their complexity means bugs can go unnoticed.
- Loading a malicious web page is enough to trigger the attack — no software to install, no user prompts.
- Heap corruption can sometimes lead to full browser sandbox escapes, system compromise, or data theft.

Original References

- Stable Channel Update for Desktop - June 5, 2023 (chromereleases.googleblog.com)
- National Vulnerability Database Entry for CVE-2023-3217
- Chromium Issue Tracker: crbug.com/1446448

Conclusion

CVE-2023-3217 highlights how serious use-after-free bugs in browser APIs—especially new tech like WebXR—can be. The best advice is simple: keep your browser updated and stay informed about security updates. This keeps you a step ahead of attackers exploiting flaws with nothing more than a tricky web page.

If you are a developer, always use caution when dealing with objects that are freed or may have uncertain lifetime, especially in event-based APIs like WebXR.

Timeline

Published on: 06/13/2023 18:15:00 UTC
Last modified on: 06/22/2023 15:47:00 UTC