Mozilla recently discovered critical memory safety bugs present in Firefox 115, Firefox ESR 115., and Thunderbird 115.. Some of these bugs showed evidence of memory corruption, and with enough effort, it is presumed that they could have been exploited to run arbitrary code. This vulnerability affects Firefox versions below 116, Firefox ESR versions below 115.1, and Thunderbird versions below 115.1. In this post, we'll discuss the technical details of these memory safety bugs, provide code snippets to demonstrate the problems, and offer steps to mitigate the risks.

Code Snippet

Consider the following code snippet, which is a simplified example of the issues found in Mozilla's products:

#include <iostream>

int main() {
  int *ptr = new int[10];
  ptr[10] = 42;
  std::cout << "Value at ptr[10]: " << ptr[10] << std::endl;
  delete[] ptr;
  return ;

In this code snippet, we have a dynamically allocated array of integers with a size of 10. However, we then attempt to set the value at index 10 (which is out of bounds) to 42. This is a prime example of memory corruption, which could lead to arbitrary code execution if exploited carefully.

Exploit Details

The exploit for this vulnerability, if successful, would involve tricking the program into accessing memory it should not have access to. This could result in crashing the program, stealing sensitive data, or executing arbitrary code on the user's system.

Crafting a specific payload that can take advantage of the vulnerability.

3. Delivering the payload to the target system, possibly through a malicious website or phishing attack.

Original References

The official CVE entry for this vulnerability can be found here: CVE-2023-4057

Mozilla's security advisory regarding this issue can be found at the following link: Mozilla Foundation Security Advisory

To protect your system from this critical memory safety vulnerability, it is crucial to

1. Update your Firefox, Firefox ESR, and Thunderbird installations to the latest versions (Firefox 116, Firefox ESR 115.1, and Thunderbird 115.1 respectively).

Be cautious when visiting untrusted websites or opening email attachments from unfamiliar sources.

3. Regularly apply security updates to your operating system and other software to minimize overall risk.


The memory safety bugs in Firefox 115, Firefox ESR 115., and Thunderbird 115. pose a significant risk, as they can be exploited to run arbitrary code on a user's system. It is essential for users to update their installations to the latest versions and exercise caution while browsing the web or opening email attachments. Regular application of security updates across the entire software stack helps to minimize risks and keeps systems protected against such vulnerabilities.


Published on: 08/01/2023 16:15:00 UTC
Last modified on: 08/07/2023 14:15:00 UTC