A significant vulnerability, CVE-2022-22764, has been discovered within the Mozilla Firefox web browser, Thunderbird email client, and the Firefox Extended Support Release (ESR) browser. This vulnerability was identified by Mozilla developers Paul Adenot and the Mozilla Fuzzing Team and impacts Firefox versions earlier than 97, Thunderbird versions earlier than 91.6, and Firefox ESR versions earlier than 91.6. In this post, we will provide an in-depth analysis of the memory safety bugs found in Firefox 96 and Firefox ESR 91.5, the code snippets associated with this vulnerability, and links to the original references and exploit details.

Memory safety bugs in Firefox 96 and Firefox ESR 91.5

According to the Mozilla developers, the memory safety bugs detected in Firefox 96 and Firefox ESR 91.5 indicate evidence of memory corruption. Given enough time and effort, these memory corruption issues could potentially be exploited by attackers to execute arbitrary code in the affected systems.

It's important to note that memory corruption can lead to unpredictable behavior of applications and, in some cases, can even result in unauthorized access to sensitive data or unintended control flow changes. These vulnerabilities pose serious threats to the security, privacy, and integrity of the affected systems and applications.

The following code snippet demonstrates a simple example of memory corruption

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main() {
    int *pointer_a = malloc(sizeof(int) * 10);
    int *pointer_b = malloc(sizeof(int) * 10);

    memset(pointer_a, , sizeof(int) * 10);
    memcpy(pointer_a, pointer_b, sizeof(int) * 25); // Memory corruption caused by wrong size calculation

    return ;

As shown in the example above, the memcpy operation with an incorrect size value is causing the memory corruption. In the context of CVE-2022-22764, this example serves as an analogy to demonstrate the potential memory corruption that may occur in the Firefox, Thunderbird, and Firefox ESR applications, making them susceptible to exploitation.

1. Mozilla Foundation Security Advisory 2022-12: https://www.mozilla.org/en-US/security/advisories/mfsa2022-12/

2. Mozilla Foundation Security Advisory 2022-13: https://www.mozilla.org/en-US/security/advisories/mfsa2022-13/

3. NVD - CVE-2022-22764: https://nvd.nist.gov/vuln/detail/CVE-2022-22764


To protect your systems from this vulnerability, it is imperative to update Firefox, Thunderbird, and Firefox ESR to the latest versions:

Firefox ESR: Update to version 91.6 or later

By applying these updates, you will effectively eliminate the memory safety bugs present in the earlier versions of these applications, and safeguard them against potential exploits.


CVE-2022-22764 is a critical vulnerability that affects Firefox 96, Thunderbird, and Firefox ESR, and exposes them to potential exploits based on the memory safety bugs discovered. By understanding this vulnerability, acknowledging the associated risks, and applying the necessary updates, you can protect your systems and data from potential attackers. Stay informed and vigilant about the latest security developments to maintain a strong and secure digital presence.


Published on: 12/22/2022 20:15:00 UTC
Last modified on: 12/30/2022 14:59:00 UTC