Sandbox escape in the Responsive Design Mode 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
/**
* Conceptual Proof of Concept for CVE-2026-4692
* Demonstrates triggering the Responsive Design Mode context
* to attempt a sandbox escape.
* Note: Actual exploit code is omitted for security reasons.
*/
function triggerExploit() {
console.log("[+] Attempting to trigger Responsive Design Mode vulnerability...");
try {
// 1. Simulate the vulnerable condition in Responsive Design Mode
// Attackers often manipulate the viewport or user-agent strings to trigger specific paths.
let vulnerableMode = document.designMode;
// 2. Trigger the sandbox bypass logic
// This is a hypothetical representation of the vulnerability trigger.
if (window.location.protocol === 'http:') { // Hypothetical condition
// Attempting to break out of the sandbox
window.postMessage({
type: 'sandbox_escape',
payload: 'malicious_code_execution'
}, '*');
}
// 3. If successful, the attacker would gain system access
console.log("[+] Exploit triggered. Checking for sandbox escape...");
} catch (error) {
console.error("[-] Exploit failed: " + error.message);
}
}
// Auto-execute
triggerExploit();