CVE-2022-1308 is a serious "use after free" vulnerability found in Google Chrome, specifically within the Back-Forward Cache (BFCache) feature, that existed up to version 100..4896.88. This flaw could let a remote attacker cause heap corruption — possibly leading to a browser crash or, in the worst cases, remote code execution — just by getting a victim to visit a specially crafted HTML page.

> CVE Report:  
> CVE-2022-1308 on NVD  
> Chromium Issue #1307512 (may require permissions)

Let’s break down exactly what this means, how attackers might have exploited this, and walk through a simplified proof-of-concept code snippet.

What is "Use After Free"?

A “use after free” vulnerability occurs when a program continues to use memory after it’s been released (or "freed"). This often leads to memory corruption, crashes, or let’s an attacker run their code since they may influence what gets stored in that memory.

In this vulnerability, the bug was in BFCache, Chrome’s feature to make back/forward navigation instant by saving whole pages in memory.

Who Was Affected?

Any user running Google Chrome prior to version 100..4896.88 on Windows, macOS, or Linux could be affected. (Many Chromium-based browsers may have inherited this issue.)

Exploit Details: How Could Attackers Abuse This?

The core idea:

This code interacts with how Chrome stores or discards pages in BFCache.

3. When the user navigates away (and maybe comes back/back-forward), the JS triggers the bug — accessing a browser object that's already been "freed."  
4. If the attacker controls what gets "re-used" (spraying the heap), they could execute their own code in the context of the browser.

Here’s a very simplified snippet, adapted for educational purposes only

<!--
  Save as 'exploit.html', then open and navigate away.
  This is not a live exploit, but demonstrates the mechanism.
-->
<!DOCTYPE html>
<html>
  <head>
    <title>CVE-2022-1308 Demo</title>
    <script>
      // Function that sets up a BFCache scenario:
      function triggerUseAfterFree() {
        // Step 1: Add a large DOM object, keep a reference
        let div = document.createElement('div');
        document.body.appendChild(div);

        // Step 2: Set up state so page is cacheable
        window.onunload = () => {};

        // Step 3: Navigate away and back
        setTimeout(() => {
          location.href = 'about:blank'; // Force navigation, triggers BFCache
          // On return, Chrome may try to reuse 'div' that could be freed
        }, 100);
      }

      window.onload = triggerUseAfterFree;
    </script>
  </head>
  <body>
    <h1>Triggering BFCache Use After Free</h1>
  </body>
</html>

What happens:
Under the hood, a cleverly prepared page can force Chrome to keep (or reuse) certain JavaScript objects, while the browser background process actually freed them. Future access from JS after navigation causes unpredictable behavior — the foundation for a heap corruption exploit.

*Note:* Real-world exploits would use *heap spraying* and more precise object control, but the above is the general tactic for demonstration.

Wide Impact: All major platforms, all Chrome users prior to patch.

- Advanced Persistence: The bug sits in browsing history and page restore mechanisms (not just normal navigation).

Was It Exploited in the Wild?

At the time of reporting, there was no known public exploitation, but these kinds of bugs are prime targets for attackers — they’re hard to find but often weaponized.

How to Stay Safe: Update Your Browser

If you haven’t already, make sure you’re running at least Google Chrome 100..4896.88 or later.
- Go to chrome://settings/help to check your version.

References

- CVE-2022-1308 (NVD)
- Google Chrome Release blog
- Chromium Security Site
- Explained: BFCache

Final Thoughts

CVE-2022-1308 is a good example of how modern browsers, with advanced performance features like BFCache, can have complex security bugs. Even code that tries to make your browser faster can sometimes become a vector for attackers.

Always keep your browser up-to-date — and know that sometimes, just one crafted HTML page is all it takes for an attacker to try to break your defenses.


*This article was crafted exclusively for educational understanding of browser security. Please do not use this knowledge for malicious purposes. Protect yourself and your users: stay patched and stay alert!*

Timeline

Published on: 07/25/2022 14:15:00 UTC
Last modified on: 08/15/2022 11:16:00 UTC