A newly discovered vulnerability, identified as CVE-2025-1018, has been found to impact Mozilla Firefox and Thunderbird versions below 135. The vulnerability is related to the fullscreen notification being prematurely hidden when the user quickly re-requests fullscreen mode. This could potentially be leveraged by an attacker to perform spoofing attacks on affected users.

Details of the vulnerability

The fullscreen notification is an essential security feature that alerts users when websites request to be displayed in fullscreen mode. It helps users stay informed and aware of possible phishing and spoofing attempts to deceive them into providing sensitive information.

The vulnerability affects Firefox and Thunderbird versions below 135 and specifically occurs when the user, through a series of rapid fullscreen requests, triggers the premature hiding of the fullscreen notification. By doing so, the user may be unaware that the site they are visiting is in fullscreen mode, making it easier for attackers to perform spoofing attacks.

Below is a code snippet that demonstrates how an attacker can exploit this vulnerability

function toggleFullscreen() {
  if (document.fullscreenElement) {
    document.exitFullscreen();
  } else {
    document.documentElement.requestFullscreen();
  }
}

// An attacker sets up a trap by repeatedly calling the 'toggleFullscreen' function
setInterval(toggleFullscreen, 100); // The duration can be modfified as per the attacker's preference

In the above code snippet, the toggleFullscreen function is repeatedly called using setInterval, causing rapid fullscreen requests and premature hiding of the fullscreen notification.

- Mozilla Foundation Security Advisory: MFSA2025-1018
- Firefox Release Notes: Firefox 135
- Thunderbird Release Notes: Thunderbird 135

Potential Exploits and Mitigations

Attackers can potentially exploit this vulnerability to launch a spoofing attack on affected users. By hiding the fullscreen notification, they can design websites that mimic the appearance of legitimate websites to deceive users into entering sensitive information, such as login credentials and personal data.

Users can mitigate this vulnerability by updating their Firefox and Thunderbird installations to versions 135 and above. Mozilla has addressed this vulnerability in its latest browser and email client versions, ensuring the fullscreen notification is not prematurely hidden when the user switches between fullscreen modes.

Closing Remarks

To recap, the CVE-2025-1018 vulnerability is a fullscreen notification spoofing issue that affects Firefox and Thunderbird versions below 135. Users must update their software to the latest versions to prevent potential spoofing attacks. Understanding and staying informed about such vulnerabilities is crucial for ensuring the security of one's digital information and identity.

Timeline

Published on: 02/04/2025 14:15:32 UTC
Last modified on: 02/06/2025 19:40:01 UTC