CVE-2022-26385 - Firefox Thread Management Vulnerability Leading to Use-After-Free During Shutdown

---

Introduction

Mozilla Firefox, a popular web browser, has been identified with a new vulnerability, specifically a use-after-free during shutdown (CVE-2022-26385). This vulnerability exists in Firefox versions prior to 98. In this post, we'll explore the exploit details, the potential security risks it poses, and the steps needed to mitigate the issue.

Explanation of the Vulnerability

In certain unusual circumstances, individual threads in Firefox could outlive their respective thread managers during the process of shutting down the browser. When this occurs, the result is a use-after-free scenario, which leads to a potentially exploitable crash. This is an important security issue, as it could be used by an attacker to execute arbitrary code or cause a denial of service (DoS) in the affected system.

Code Snippet

The vulnerability lies in the faulty handling of threads and their managers during shutdown.

Pseudo-code snippet

on_shutdown() {
  for each thread_manager in all_thread_managers {
    if thread_manager.is_alive() {
      // Vulnerable code
      thread_manager.cleanup()
    }
  }
}

The problem occurs when, during the cleanup() process, a still-running thread outlives its manager. This can lead to a use-after-free scenario when the memory occupied by the manager is reallocated or used elsewhere, while the thread still attempts to interact with it. This results in undefined behavior, which may include exploitable crashes.

References

1. CVE-2022-26385 Official Listing
2. Mozilla Foundation Security Advisory (MFSA)
3. Firefox 98 Release Notes

Exploit and Impact

A threat actor could exploit this vulnerability by crafting a malicious website or script that triggers multiple threads and manipulates the browser to cause an unusual shutdown scenario. The goal of the attacker would be to create conditions where a thread outlives its manager during the shutdown process. If successful, the attacker could potentially execute arbitrary code or cause a denial of service on the affected system, leading to critical security risks for the user.

The best defense against this vulnerability is to upgrade your Firefox browser to the latest version

- Firefox Download

Mozilla Firefox has addressed this vulnerability in version 98. If you are using a version prior to this, it's essential that you update your browser as soon as possible to minimize the risk of a potential exploit. Updating to the current version will help ensure that your browser has the latest patches and security fixes, keeping your system protected from known threats.


In conclusion, the CVE-2022-26385 vulnerability in Firefox is a critical issue that needs urgent attention. It involves a use-after-free scenario during browser shutdown, which can cause a potentially exploitable crash. To mitigate this risk, keep your browser updated to the latest version and stay vigilant about all available security patches.

Timeline

Published on: 12/22/2022 20:15:00 UTC
Last modified on: 12/30/2022 15:05:00 UTC