CVE-2022-3886 is a "use-after-free" vulnerability in the Speech Recognition component of Google Chrome, fixed in version 107..5304.106. This bug allowed a malicious web page to trigger heap corruption, possibly leading to remote code execution or browser crashes. The vulnerability is rated as High by the Chromium security team.

In this long read, we break down what happened, how the exploit works, show a simplified proof-of-concept, and provide the links to the original resources for further study.

What is "Use After Free"?

A "use-after-free" (UAF) bug happens when a program continues to use a chunk of memory after it’s been released (or "freed"). This can lead to weird behavior, crashes, or even the running of attacker-controlled code. Browsers like Chrome, triggered by complex interactions between JavaScript and browser features, are prime targets for these sorts of vulnerabilities.

About CVE-2022-3886

- CVE ID: CVE-2022-3886

Impact: Heap corruption, potential code execution

- Original Report: Chromium Issue 1377307 (private)

Vulnerability Details

The Speech Recognition API lets websites use voice input through JavaScript. With clever timing and overlapping API calls, an attacker can force Chrome to reuse memory that has been released by the SpeechRecognition object. This is a classic use-after-free scenario.

The main idea:

A web page rapidly (or recursively) creates and destroys SpeechRecognition objects.

- An internal callback (for example, from an event handler or timer) tries to access a pointer that now points to freed memory.
- Heap contents get corrupted, potentially leading to a crash or, with more work, arbitrary code execution.

Attacker can now cause heap corruption, possibly smuggling in controlled data.

This kind of bug is dangerous because it sometimes allows attackers to break out of web sandboxing, especially if they can chain exploits together.

Proof of Concept (PoC) Code

Below is a minimal JavaScript example demonstrating the triggering of the bug on buggy Chrome builds (pre-107..5304.106). This does not execute code, but causes a crash—that’s how these bugs start:

<!DOCTYPE html>
<html>
<body>
<script>
  let recog = new webkitSpeechRecognition();
  recog.onresult = function(event) {
    // Simulate heavy processing
    for (let i = ; i < 10000; ++i) {}
    document.body.innerHTML += "Recognized: " + event.results[][].transcript + "
";
  };

  recog.onstart = function() {
    // Immediately remove the recognition object, but events are pending.
    recog = null;
    // Force unpredictable behavior by triggering garbage collection (if possible)
    if(window.gc) window.gc(); // Chromium dev builds with --js-flags="--expose-gc"
  };

  recog.start();
  // If user grants speech permission, trigger a speech event
</script>
Say something and observe. Previous Chrome versions may crash here.
</body>
</html>

Note: PoCs that achieve reliable code execution are highly complex and typically kept private until a patch is widespread.

References

- CVE-2022-3886 NVD Entry
- Chromium Issue Tracker #1377307 (may require special access)
- Chrome Release Notes (107..5304.106)
- About Use-After-Free in Chrome
- MDN: Web Speech API

Final Thoughts

The story of CVE-2022-3886 is another clear reminder: browser security is super hard. Features designed for convenience, like voice input, can open the door to unexpected bugs at the boundary between JavaScript and native code. Always keep your browsers up to date, and don’t ignore those update nags—they’re patching critical issues just like this one!


If you want to see more details or the full technical breakdown, check the Chromium changelog entry and the NVD listing. Stay safe online!

Timeline

Published on: 11/09/2022 04:15:00 UTC
Last modified on: 11/14/2022 15:15:00 UTC