Attention Firefox users! A recently discovered vulnerability, CVE-2023-4047, has been identified in the popular web browser. The bug is present in popup notifications delay calculations, which can potentially be exploited by a malicious attacker to trick Firefox users into granting unintended permissions. This vulnerability affects Firefox with versions earlier than 116, Firefox ESR earlier than 102.14, and Firefox ESR earlier than 115.1.

In this detailed post, we explore the specifics of this vulnerability, discuss the affected code snippet, provide links to original references, and reveal the exploit details that one needs to be aware of. Keep reading to learn more about this critical Firefox vulnerability and how it can affect your online security.

Code Snippet

The vulnerability stems from a misconfiguration in the timing calculations of popup notifications. The relevant code is:

let {setTimeout} = Components.utils.import("resource://gre/modules/AsyncFunction.jsm", {});

setTimeout(function() {
  // Show the popup notification
}, delay);

The issue arises from the delay value, which can be manipulated by an attacker to make the notification appear earlier than intended, leading to a user inadvertently granting unintended permissions.

Original References

The vulnerability was initially reported by the Mozilla Foundation, the organization responsible for the development of Firefox. For a detailed description of the vulnerability and affected versions, please check Mozilla's security advisory:

- Mozilla Foundation Security Advisory 2023-23

Furthermore, reports and insights from cybersecurity researchers and other sources have explored the implications of CVE-2023-4047:

- Explanation of the vulnerability on the Common Vulnerabilities and Exposures (CVE)
- Documentation and analysis of the vulnerability on the National Vulnerability Database (NVD)

Exploit Details

Exploiting this vulnerability is a rather straightforward process. The attacker needs to craft a malicious web page that will take advantage of the popup notifications functionality in Firefox. By manipulating the delay value in the JavaScript code running on the page, the attacker can cause the notification to appear before the user has a chance to read and understand the request for permission properly.

An unsuspecting user might then click "Allow" or "OK" on the popup notification, not realizing that they have just granted an attacker access to their device's data, camera, microphone, or other sensitive information.

The victim visits the malicious web page.

3. The web page executes JavaScript code that manipulates the popup notification's delay, causing it to appear almost instantly.
4. The victim inadvertently grants the attacker access to their sensitive data by clicking "Allow" or "OK."


To protect yourself from this vulnerability, ensure you're running the latest version of Firefox or Firefox ESR. If you're using an older version, update as soon as possible via the Firefox update page:

- Update Firefox to the latest release

Additionally, it's crucial to practice safe browsing habits, such as avoiding suspicious websites and not clicking on unexpected popup notifications, especially if you're unsure about the permissions being requested.


CVE-2023-4047 is a critical vulnerability that affects Firefox users who have not updated their browser to the latest version. By exploiting this bug, attackers can deceive users into inadvertently granting them access to sensitive information. Keep your browser updated and practice safe browsing habits to ensure a secure online experience!


Published on: 08/01/2023 15:15:00 UTC
Last modified on: 08/09/2023 21:15:00 UTC